<SUBMISSION>
<ACCESSION-NUMBER>0000950123-06-011832
<TYPE>S-1/A
<PUBLIC-DOCUMENT-COUNT>2
<FILING-DATE>20060921
<DATE-OF-FILING-DATE-CHANGE>20060921
<FILER>
<COMPANY-DATA>
<CONFORMED-NAME>COMMVAULT SYSTEMS INC
<CIK>0001169561
<ASSIGNED-SIC>7372
<IRS-NUMBER>000000000
<STATE-OF-INCORPORATION>DE
</COMPANY-DATA>
<FILING-VALUES>
<FORM-TYPE>S-1/A
<ACT>33
<FILE-NUMBER>333-132550
<FILM-NUMBER>061101680
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>2 CRESCENT PLACE
<CITY>OCEANPORT
<STATE>NJ
<ZIP>07757-0900
<PHONE>7328704000
</BUSINESS-ADDRESS>
</FILER>
<DOCUMENT>
<TYPE>S-1/A
<SEQUENCE>1
<FILENAME>y24537a6sv1za.htm
<DESCRIPTION>S-1/A
<TEXT>
<HTML>
<HEAD>
<TITLE>S-1/A</TITLE>
</HEAD>
<BODY bgcolor="#FFFFFF">
<!-- PAGEBREAK -->
<H5 align="left" style="page-break-before:always">&nbsp;</H5><P>

<DIV align="left"><FONT size="1">

</FONT></DIV>

<DIV align="center" style="font-size: 10.0pt;color: #000000; background: #ffffff;">
<B>As filed with the Securities and Exchange Commission on
September&nbsp;21, 2006</B>
</DIV>

<DIV align="left"><FONT size="1">

</FONT></DIV>

<DIV align="right" style="font-size: 10.0pt;color: #000000; background: #ffffff;">
<B>Registration No.&nbsp;333-132550</B>
</DIV>

<DIV align="center" style="font-size: 6.0pt;color: #000000; background: #ffffff;">
<DIV style="width: 100%; border-top: 2.0pt solid black; font-size: 1pt">&nbsp;</DIV>
</DIV>

<DIV align="center" style="font-size: 3.0pt;color: #000000; background: #ffffff;">
<DIV style="width: 100%; border-top: 1.0pt solid black; font-size: 1pt">&nbsp;</DIV>
</DIV>

<DIV align="center" style="font-size: 14.0pt;color: #000000; background: #ffffff; margin-top: 4pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">
<B>SECURITIES AND EXCHANGE COMMISSION</B>
</DIV>

<DIV align="center" style="font-size: 12.0pt;color: #000000; background: #ffffff;">
<B>Washington,&nbsp;D.C. 20549</B>
</DIV>

<DIV align="left"><FONT size="1">

</FONT></DIV>

<DIV align="center" style="font-size: 12.0pt;color: #000000; background: #ffffff; margin-top: 6pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">
<B>Amendment No.&nbsp;6</B>
</DIV>

<DIV align="left"><FONT size="1">

</FONT></DIV>

<DIV align="center" style="font-size: 12.0pt;color: #000000; background: #ffffff;">
<B>to</B>
</DIV>

<DIV align="center" style="font-size: 18.0pt;color: #000000; background: #ffffff;">
<B>FORM&nbsp;<FONT style="white-space: nowrap">S-1</FONT></B>
</DIV>

<DIV align="center" style="font-size: 12.0pt;color: #000000; background: #ffffff;">
<B>REGISTRATION STATEMENT</B>
</DIV>

<DIV align="center" style="font-size: 12.0pt;color: #000000; background: #ffffff;">
<B>UNDER</B>
</DIV>

<DIV align="center" style="font-size: 12.0pt;color: #000000; background: #ffffff;">
<B>THE SECURITIES ACT OF 1933</B>
</DIV>

<DIV align="center" style="font-size: 24.0pt;color: #000000; background: #ffffff; margin-top: 6pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">
<B>CommVault Systems, Inc.</B>
</DIV>

<DIV align="center" style="font-size: 8.0pt;color: #000000; background: #ffffff;">
<I>(Exact name of registrant as specified in its charter)</I>
</DIV>

<CENTER>
<TABLE width="100%" align="center" cellspacing="0" cellpadding="0" border="0" style="font-size: 10.0pt; margin-top: 6pt; ">

<TR style="font-size: 1pt;">
    <TD width="34%">&nbsp;</TD>
    <TD width="3%">&nbsp;</TD>
    <TD width="32%">&nbsp;</TD>
    <TD width="3%">&nbsp;</TD>
    <TD width="28%">&nbsp;</TD>
</TR>

<TR>
    <TD align="center" valign="top">
    <B>Delaware</B></TD>
    <TD>&nbsp;</TD>
    <TD align="center" valign="top">
    <B>7372</B></TD>
    <TD>&nbsp;</TD>
    <TD align="center" valign="top">
    <B>22-3447504</B></TD>
</TR>

<TR>
    <TD align="center" valign="top">
    <I>(State of incorporation)</I></TD>
    <TD>&nbsp;</TD>
    <TD align="center" valign="top">
    <I>(Primary Standard Industrial<BR>
     Classification Code Number)</I></TD>
    <TD>&nbsp;</TD>
    <TD align="center" valign="top">
    <I>(I.R.S. Employer<BR>
    Identification No.)</I></TD>
</TR>

</TABLE>
</CENTER>

<DIV align="center" style="font-size: 10.0pt;color: #000000; background: #ffffff; margin-top: 6pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">
<B>2 Crescent Place</B>
</DIV>

<DIV align="center" style="font-size: 10.0pt;color: #000000; background: #ffffff;">
<B>Oceanport, New Jersey 07757</B>
</DIV>

<DIV align="center" style="font-size: 10.0pt;color: #000000; background: #ffffff;">
<B>(732)&nbsp;870-4000</B>
</DIV>

<DIV align="center" style="font-size: 8.0pt;color: #000000; background: #ffffff;">
<I>(Address, including zip code, and telephone number, including
area code, of registrant&#146;s principal executive offices)</I>
</DIV>

<DIV align="center" style="font-size: 10.0pt;color: #000000; background: #ffffff; margin-top: 6pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">
<B>N. Robert Hammer</B>
</DIV>

<DIV align="center" style="font-size: 10.0pt;color: #000000; background: #ffffff;">
<B>Chairman, President and Chief Executive Officer</B>
</DIV>

<DIV align="center" style="font-size: 10.0pt;color: #000000; background: #ffffff;">
<B>CommVault Systems, Inc.</B>
</DIV>

<DIV align="center" style="font-size: 10.0pt;color: #000000; background: #ffffff;">
<B>2 Crescent Place</B>
</DIV>

<DIV align="center" style="font-size: 10.0pt;color: #000000; background: #ffffff;">
<B>Oceanport, New Jersey 07757</B>
</DIV>

<DIV align="center" style="font-size: 10.0pt;color: #000000; background: #ffffff;">
<B>(732)&nbsp;870-4000</B>
</DIV>

<DIV align="center" style="font-size: 8.0pt;color: #000000; background: #ffffff;">
<I>(Name, address, including zip code, and telephone number,
including area code, of agent for service)</I>
</DIV>

<DIV align="center" style="font-size: 10.0pt;color: #000000; background: #ffffff; margin-top: 6pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">
<B><I>Copies to:</I></B>
</DIV>

<CENTER>
<TABLE width="100%" align="center" cellspacing="0" cellpadding="0" border="0" style="font-size: 10.0pt; ">

<TR style="font-size: 1pt;">
    <TD width="53%">&nbsp;</TD>
    <TD width="3%">&nbsp;</TD>
    <TD width="44%">&nbsp;</TD>
</TR>

<TR>
    <TD align="center" valign="top">
    <B>Philip J. Niehoff,&nbsp;Esq.</B></TD>
    <TD>&nbsp;</TD>
    <TD align="center" valign="top">
    <B>William J. Whelan,&nbsp;III,&nbsp;Esq.</B></TD>
</TR>

<TR>
    <TD align="center" valign="top">
    <B>John R. Sagan,&nbsp;Esq.</B></TD>
    <TD>&nbsp;</TD>
    <TD align="center" valign="top">
    <B>LizabethAnn R. Eisen,&nbsp;Esq.</B></TD>
</TR>

<TR>
    <TD align="center" valign="top">
    <B>Mayer, Brown, Rowe&nbsp;&#38; Maw LLP</B></TD>
    <TD>&nbsp;</TD>
    <TD align="center" valign="top">
    <B>Cravath, Swaine&nbsp;&#38; Moore LLP</B></TD>
</TR>

<TR>
    <TD align="center" valign="top">
    <B>71 South Wacker Drive</B></TD>
    <TD>&nbsp;</TD>
    <TD align="center" valign="top">
    <B>825 Eighth Avenue</B></TD>
</TR>

<TR>
    <TD align="center" valign="top">
    <B>Chicago, Illinois 60606</B></TD>
    <TD>&nbsp;</TD>
    <TD align="center" valign="top">
    <B>New York, New York 10019</B></TD>
</TR>

<TR>
    <TD align="center" valign="top">
    <B>(312) 782-0600</B></TD>
    <TD>&nbsp;</TD>
    <TD align="center" valign="top">
    <B>(212)&nbsp;474-1000</B></TD>
</TR>

</TABLE>
</CENTER>

<DIV align="left" style="font-size: 10.0pt;color: #000000; background: #ffffff; margin-top: 6pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
<B>Approximate date of commencement of proposed sale to the
public:</B> As soon as practicable after this Registration
Statement becomes effective.
</DIV>

<DIV align="left" style="font-size: 10.0pt;color: #000000; background: #ffffff; margin-top: 3pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
If any of the securities being registered on this Form are to be
offered on a delayed or continuous basis pursuant to
Rule&nbsp;415 under the Securities Act of 1933, check the
following
box.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<FONT face="wingdings">&#111;
</FONT>
</DIV>

<DIV align="left" style="font-size: 10.0pt;color: #000000; background: #ffffff; margin-top: 3pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
If this Form is filed to register additional securities for an
offering pursuant to Rule&nbsp;462(b) under the Securities Act,
check the following box and list the Securities Act registration
statement number of the earlier effective registration statement
for the same
offering.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<FONT face="wingdings">&#111;
</FONT>
</DIV>

<DIV align="left" style="font-size: 10.0pt;color: #000000; background: #ffffff; margin-top: 3pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
If this Form is a post-effective amendment filed pursuant to
Rule&nbsp;462(c) under the Securities Act, check the following
box and list the Securities Act registration statement number of
the earlier effective registration statement for the same
offering.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<FONT face="wingdings">&#111;
</FONT>
</DIV>

<DIV align="left" style="font-size: 10.0pt;color: #000000; background: #ffffff; margin-top: 3pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
If this Form is a post-effective amendment filed pursuant to
Rule&nbsp;462(d) under the Securities Act, check the following
box and list the Securities Act registration statement number of
the earlier effective registration statement for the same
offering.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<FONT face="wingdings">&#111;
</FONT>
</DIV>

<DIV align="center" style="font-size: 10.0pt;color: #000000; background: #ffffff; margin-top: 6pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">
<B>CALCULATION OF REGISTRATION FEE</B>
</DIV>

<CENTER>
<TABLE width="100%" align="center" cellspacing="0" cellpadding="0" border="0" style="font-size: 10.0pt; margin-top: 6pt; ">

<TR style="font-size: 1pt;">
    <TD width="40%">&nbsp;</TD>
    <TD width="3%">&nbsp;</TD>
    <TD width="26%">&nbsp;</TD>
    <TD width="3%">&nbsp;</TD>
    <TD width="28%">&nbsp;</TD>
</TR>


<TR valign="bottom" style="font-size: 1px">
    <TD colspan="5" align="center" nowrap style="border-top: 1pt solid #000000;">&nbsp;</TD>
</TR>


<TR valign="bottom" style="font-size: 1px">
    <TD colspan="5" align="center" nowrap style="border-top: 1pt solid #000000;">&nbsp;</TD>
</TR>

<TR style="font-size: 8.0pt;">
    <TD align="center" nowrap><B>Title of Each Class of</B></TD>
    <TD>&nbsp;</TD>
    <TD align="center" nowrap><B>Proposed Maximum</B></TD>
    <TD>&nbsp;</TD>
    <TD align="center" nowrap><B>Amount of</B></TD>
</TR>

<TR style="font-size: 8.0pt;">
    <TD align="center" nowrap><B>Securities to Be Registered</B></TD>
    <TD>&nbsp;</TD>
    <TD align="center" nowrap><B>Aggregate Offering Price</B></TD>
    <TD>&nbsp;</TD>
    <TD align="center" nowrap><B>Registration Fee(1)</B></TD>
</TR>

<TR valign="bottom" style="font-size: 1px">
    <TD colspan="5" align="left" style="border-top: 1pt solid #000000;">&nbsp;</TD>

</TR>

<TR>
    <TD align="left" valign="top">
    <DIV style="margin-left: 10px; text-indent: -10px">
    Common Stock, par value $0.01&nbsp;per share</DIV>
    </TD>
    <TD>&nbsp;</TD>
    <TD align="center" valign="top">
    $185,277,781</TD>
    <TD>&nbsp;</TD>
    <TD align="center" valign="top">
    $19,825(2)</TD>
</TR>

<TR valign="bottom" style="font-size: 1px">
    <TD colspan="5" align="left" style="border-top: 1pt solid #000000;">&nbsp;</TD>

</TR>

<TR valign="bottom" style="font-size: 1px">
    <TD colspan="5" align="left" style="border-top: 1pt solid #000000;">&nbsp;</TD>

</TR>

</TABLE>
</CENTER>

<DIV style="margin-top: 3pt; margin-left: 0; margin-right: 0; margin-bottom: 0; color: #000000; background: #ffffff;"></DIV>

<TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10.0pt;color: #000000; background: #ffffff;">

<TR>
    <TD width="4%"></TD>
    <TD width="96%"></TD>
</TR>

<TR valign="top">
    <TD>(1)&nbsp;</TD>
    <TD align="left">
    Calculated pursuant to Rule&nbsp;457(o) under the Securities Act
    of 1933.</TD>
</TR>

<TR>
    <TD style="font-size: 3.0pt">&nbsp;</TD>
</TR>

<TR valign="top">
    <TD>(2)&nbsp;</TD>
    <TD align="left">
    $16,050 previously paid.</TD>
</TR>

</TABLE>

<DIV align="left" style="font-size: 10.0pt;color: #000000; background: #ffffff; margin-top: 6pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
<B>The Registrant hereby amends this Registration Statement on
such date or dates as may be necessary to delay its effective
date until the Registrant shall file a further amendment which
specifically states that this Registration Statement shall
thereafter become effective in accordance with Section&nbsp;8(a)
of the Securities Act of 1933 or until the Registration
Statement shall become effective on such date as the Commission
acting pursuant to said section&nbsp;8(a), may determine.</B>
</DIV>

<DIV align="center" style="font-size: 3.0pt;color: #000000; background: #ffffff; margin-top: 3pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">
<DIV style="width: 100%; border-top: 1.0pt solid black; font-size: 1pt">&nbsp;</DIV>
</DIV>

<DIV align="center" style="font-size: 4.0pt;color: #000000; background: #ffffff;">
<DIV style="width: 100%; border-top: 2.0pt solid black; font-size: 1pt">&nbsp;</DIV>
</DIV>

<!-- PAGEBREAK -->
<P><HR noshade><P>
<H5 align="left" style="page-break-before:always">&nbsp;</H5><P>

<DIV align="center" style="font-size: 10.0pt;color: #000000; background: #ffffff; margin-top: 18pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">
<B>PART&nbsp;II</B>
</DIV>

<DIV align="center" style="font-size: 10.0pt;color: #000000; background: #ffffff; margin-top: 6pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">
<B>INFORMATION NOT REQUIRED IN PROSPECTUS</B>
</DIV>

<DIV style="margin-top: 12pt; margin-left: 0; margin-right: 0; margin-bottom: 0; color: #000000; background: #ffffff;"></DIV>

<TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10.0pt;color: #000000; background: #ffffff;">

<TR>
    <TD width="9%"></TD>
    <TD width="91%"></TD>
</TR>

<TR valign="top">
    <TD><B>Item&nbsp;13.</B></TD>
    <TD>
    <B><I>Other Expenses of Issuance and Distribution.</I></B></TD>
</TR>

</TABLE>

<DIV align="left" style="font-size: 10.0pt;color: #000000; background: #ffffff; margin-top: 6pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
The following table shows the expenses to be incurred in
connection with the offering described in this registration
statement, all of which will be paid by the registrant. All
amounts are estimates, other than the SEC registration fee, the
NASD filing fee and the NASDAQ listing fee.
</DIV>

<CENTER>
<TABLE width="100%" align="center" cellspacing="0" cellpadding="0" border="0" style="font-size: 10.0pt; margin-top: 6pt; ">

<TR style="font-size: 1pt;">
    <TD width="3%">&nbsp;</TD>
    <TD width="81%">&nbsp;</TD>
    <TD width="3%">&nbsp;</TD>
    <TD width="1%">&nbsp;</TD>
    <TD width="11%">&nbsp;</TD>
    <TD width="1%">&nbsp;</TD>
</TR>

<TR valign="bottom" bgcolor="#cceeff">
    <TD colspan="2" align="left" valign="top">
    <DIV style="margin-left: 10px; text-indent: -10px">
    SEC registration fee</DIV>
    </TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="bottom">$</TD>
    <TD align="right" valign="bottom" nowrap>19,825</TD>
    <TD>&nbsp;</TD>
</TR>

<TR>
    <TD colspan="2" align="left" valign="top">
    <DIV style="margin-left: 10px; text-indent: -10px">
    NASD filing fee</DIV>
    </TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="bottom">&nbsp;</TD>
    <TD align="right" valign="bottom" nowrap>19,028</TD>
    <TD>&nbsp;</TD>
</TR>

<TR valign="bottom" bgcolor="#cceeff">
    <TD colspan="2" align="left" valign="top">
    <DIV style="margin-left: 10px; text-indent: -10px">
    NASDAQ listing fee</DIV>
    </TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="bottom">&nbsp;</TD>
    <TD align="right" valign="bottom" nowrap>125,000</TD>
    <TD>&nbsp;</TD>
</TR>

<TR>
    <TD colspan="2" align="left" valign="top">
    <DIV style="margin-left: 10px; text-indent: -10px">
    Accounting fees and expenses</DIV>
    </TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="bottom">&nbsp;</TD>
    <TD align="right" valign="bottom" nowrap>1,200,000</TD>
    <TD>&nbsp;</TD>
</TR>

<TR valign="bottom" bgcolor="#cceeff">
    <TD colspan="2" align="left" valign="top">
    <DIV style="margin-left: 10px; text-indent: -10px">
    Legal fees and expenses</DIV>
    </TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="bottom">&nbsp;</TD>
    <TD align="right" valign="bottom" nowrap>625,000</TD>
    <TD>&nbsp;</TD>
</TR>

<TR>
    <TD colspan="2" align="left" valign="top">
    <DIV style="margin-left: 10px; text-indent: -10px">
    Printing and engraving expenses</DIV>
    </TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="bottom">&nbsp;</TD>
    <TD align="right" valign="bottom" nowrap>425,000</TD>
    <TD>&nbsp;</TD>
</TR>

<TR valign="bottom" bgcolor="#cceeff">
    <TD colspan="2" align="left" valign="top">
    <DIV style="margin-left: 10px; text-indent: -10px">
    Transfer agent&#146;s fees</DIV>
    </TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="bottom">&nbsp;</TD>
    <TD align="right" valign="bottom" nowrap>20,000</TD>
    <TD>&nbsp;</TD>
</TR>

<TR>
    <TD colspan="2" align="left" valign="top">
    <DIV style="margin-left: 10px; text-indent: -10px">
    Miscellaneous</DIV>
    </TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="bottom">&nbsp;</TD>
    <TD align="right" valign="bottom" nowrap>66,147</TD>
    <TD>&nbsp;</TD>
</TR>

<TR valign="bottom" style="font-size: 1px">
    <TD colspan="2">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD colspan="2" align="left" style="border-top: 1pt solid #000000;">&nbsp;</TD>
    <TD>&nbsp;</TD>

</TR>

<TR valign="bottom" bgcolor="#cceeff">
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    <DIV style="margin-left: 10px; text-indent: -10px">
    Total</DIV>
    </TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="bottom">$</TD>
    <TD align="right" valign="bottom" nowrap>2,500,000</TD>
    <TD>&nbsp;</TD>
</TR>

<TR valign="bottom" style="font-size: 1px">
    <TD colspan="2">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD colspan="2" align="left" style="border-top: 3pt double #000000;">&nbsp;</TD>
    <TD>&nbsp;</TD>

</TR>

</TABLE>
</CENTER>

<DIV align="left" style="font-size: 3.0pt;color: #000000; background: #ffffff; margin-top: 6pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">
<DIV style="width: 18%; border-top: 1.0pt solid black; font-size: 1pt">&nbsp;</DIV>
</DIV>

<DIV style="margin-top: 15pt; margin-left: 0; margin-right: 0; margin-bottom: 0; color: #000000; background: #ffffff;"></DIV>

<TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10.0pt;color: #000000; background: #ffffff;">

<TR>
    <TD width="9%"></TD>
    <TD width="91%"></TD>
</TR>

<TR valign="top">
    <TD><B>Item&nbsp;14.</B></TD>
    <TD>
    <B><I>Indemnification of Directors and Officers.</I></B></TD>
</TR>

</TABLE>

<DIV align="left" style="font-size: 10.0pt;color: #000000; background: #ffffff; margin-top: 6pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
Section&nbsp;102 of the Delaware General Corporation Law
(&#147;DGCL&#148;), as amended, allows a corporation to
eliminate the personal liability of directors of a corporation
to the corporation or its stockholders for monetary damages for
a breach of fiduciary duty as a director, except where the
director breached his duty of loyalty, failed to act in good
faith, engaged in intentional misconduct or knowingly violated a
law, authorized the payment of a dividend or approved a stock
repurchase in violation of Delaware law or obtained an improper
personal benefit.
</DIV>

<DIV align="left" style="font-size: 10.0pt;color: #000000; background: #ffffff; margin-top: 6pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
Section&nbsp;145 of the DGCL provides, among other things, that
a corporation may indemnify any person who was or is a party or
is threatened to be made a party to any threatened, pending or
completed action, suit or proceeding (other than an action by or
in the right of the corporation) by reason of the fact that the
person is or was a director, officer, agents or employee of the
corporation or is or was serving at the corporation&#146;s
request as a director, officer, agent or employee of another
corporation, partnership, joint venture, trust or other
enterprise, against expenses, including attorneys&#146; fees,
judgments, fines and amounts paid in settlement actually and
reasonably incurred by the person in connection with such
action, suit or proceeding. The power to indemnify applies
(a)&nbsp;if such person is successful on the merits or otherwise
in defense of any action, suit or proceeding or (b)&nbsp;if such
person acted in good faith and in a manner he reasonably
believed to be in the best interests, or not opposed to the best
interests, of the corporation, and with respect to any criminal
action or proceeding, had no reasonable cause to believe his
conduct was unlawful. The power to indemnify applies to actions
brought by or in the right of the corporation as well, but only
to the extent of expenses (including attorneys&#146; fees but
excluding amounts paid in settlement) actually and reasonably
incurred in the defense or settlement of such action and not to
any satisfaction of judgment or settlement of the claim itself,
and with the further limitation that in such actions no
indemnification shall be made in the event of any adjudication
of negligence or misconduct in the performance of duties to the
corporation, unless the court believes that in light of all the
circumstances indemnification should apply.
</DIV>

<DIV align="left" style="font-size: 10.0pt;color: #000000; background: #ffffff; margin-top: 6pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
Section&nbsp;174 of the DGCL provides, among other things, that
a director, who willfully or negligently approves of an unlawful
payment of dividends or an unlawful stock purchase or
redemption, shall be held liable for such actions. A director
who was either absent when the unlawful actions were approved or
dissented at the time, may avoid liability by causing his or her
dissent to such actions to be entered on the
</DIV>

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<DIV align="left" style="font-size: 10.0pt;color: #000000; background: #ffffff;">
books containing the minutes of the meetings of the board of
directors at the time such actions occurred or immediately after
such absent director receives notice of the unlawful acts.
</DIV>

<DIV align="left" style="font-size: 10.0pt;color: #000000; background: #ffffff; margin-top: 6pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
Our certificate of incorporation provides that, pursuant to
Delaware law, our directors shall not be liable for monetary
damages for breach of the directors&#146; fiduciary duty of care
to us and our stockholders. This provision in the certificate of
incorporation does not eliminate the duty of care, and in
appropriate circumstances equitable remedies such as injunctive
or other forms of non-monetary relief will remain available
under Delaware law. In addition, each director will continue to
be subject to liability for breach of the director&#146;s duty
of loyalty to us or our stockholders, for acts or omissions not
in good faith or involving intentional misconduct or knowing
violations of law, for actions leading to improper personal
benefit to the director and for payment of dividends or approval
of stock repurchases or redemptions that are unlawful under
Delaware law. The provision also does not affect a
director&#146;s responsibilities under any other law, such as
the federal securities laws or state or federal environmental
laws.
</DIV>

<DIV align="left" style="font-size: 10.0pt;color: #000000; background: #ffffff; margin-top: 6pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
Our bylaws provide that we must indemnify our directors and
officers to the fullest extent permitted by Delaware law and
require us to advance litigation expenses upon our receipt of an
undertaking by or on behalf of a director or officer to repay
such advances if it is ultimately determined that such director
or officer is not entitled to indemnification. The
indemnification provisions contained in our bylaws are not
exclusive of any other rights to which a person may be entitled
by law, agreement, vote of stockholders or disinterested
directors or otherwise. We intend to obtain directors&#146; and
officers&#146; liability insurance in connection with this
offering.
</DIV>

<DIV align="left" style="font-size: 10.0pt;color: #000000; background: #ffffff; margin-top: 6pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
In addition, we have entered or, concurrently with this
offering, will enter, into agreements to indemnify our directors
and certain of our officers in addition to the indemnification
provided for in the certificate of incorporation and bylaws.
These agreements will, among other things, indemnify our
directors and some of our officers for certain expenses
(including attorneys&#146; fees), judgments, fines and
settlement amounts incurred by such person in any action or
proceeding, including any action by or in our right, on account
of services by that person as a director or officer of CommVault
or as a director or officer of any of our subsidiaries, or as a
director or officer of any other company or enterprise that the
person provides services to at our request.
</DIV>

<DIV align="left" style="font-size: 10.0pt;color: #000000; background: #ffffff; margin-top: 6pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
The underwriting agreement provides for indemnification by the
underwriters of us and our officers and directors, and by us of
the underwriters, for certain liabilities arising under the
Securities Act or otherwise in connection with this offering.
</DIV>

<DIV style="margin-top: 12pt; margin-left: 0; margin-right: 0; margin-bottom: 0; color: #000000; background: #ffffff;"></DIV>

<TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10.0pt;color: #000000; background: #ffffff;">

<TR>
    <TD width="9%"></TD>
    <TD width="91%"></TD>
</TR>

<TR valign="top">
    <TD><B>Item&nbsp;15.</B></TD>
    <TD>
    <B><I>Recent Sales of Unregistered Securities.</I></B></TD>
</TR>

</TABLE>

<DIV align="left" style="font-size: 10.0pt;color: #000000; background: #ffffff; margin-top: 6pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
Since January&nbsp;1, 2003, the registrant has sold the
following securities without registration under the Securities
Act of 1933:
</DIV>

<DIV style="margin-top: 6pt; margin-left: 0; margin-right: 0; margin-bottom: 0; color: #000000; background: #ffffff;"></DIV>

<TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10.0pt;color: #000000; background: #ffffff;">

<TR>
    <TD width="3%"></TD>
    <TD width="4%"></TD>
    <TD width="93%"></TD>
</TR>

<TR valign="top">
    <TD>&nbsp;</TD>
    <TD>(1)&nbsp;</TD>
    <TD align="left">
    In July 2003, the registrant issued an amended and restated
    warrant to purchase 1,500,000&nbsp;shares of its common stock at
    an exercise price of $12.54&nbsp;per share to EMC Investment
    Corporation, an accredited investor. The warrant expired without
    being exercised on February&nbsp;2, 2006. The amended and
    restated warrant was issued to replace a warrant to purchase
    2,232,500&nbsp;shares of the registrant&#146;s common stock at
    an exercise price of $27.14&nbsp;per share, subject to certain
    adjustments, that had been issued by the registrant to the
    holder in November 2000. The original warrant was issued to the
    holder in connection with the holder&#146;s purchase of shares
    of the registrant&#146;s Series&nbsp;BB preferred stock. No
    other persons were offered the opportunity to purchase the
    warrant or participate in the exchange and no commission or
    other remuneration was paid or given directly or indirectly to
    any person for soliciting the exchange. The issuance of the
    replacement warrant was therefore exempt from registration
    pursuant to Section&nbsp;3(a)(9) of the Securities Act.</TD>
</TR>

<TR>
    <TD style="font-size: 6.0pt">&nbsp;</TD>
</TR>

<TR valign="top">
    <TD>&nbsp;</TD>
    <TD>(2)&nbsp;</TD>
    <TD align="left">
    In September 2003, the registrant sold 4,790,802&nbsp;shares of
    registrant&#146;s Series&nbsp;CC preferred stock to four
    individuals and 21 investment funds and other investment
    entities for approximately $15&nbsp;million. Each of the
    investors was an accredited investor. The offer and sale was
    exempt</TD>
</TR>

</TABLE>

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<TR>
    <TD width="3%"></TD>
    <TD width="4%"></TD>
    <TD width="93%"></TD>
</TR>

<TR valign="top">
    <TD>&nbsp;</TD>
    <TD></TD>
    <TD align="left">
    from registration pursuant to Section&nbsp;4(2) of the
    Securities Act and Regulation&nbsp;D promulgated thereunder.</TD>
</TR>

<TR>
    <TD style="font-size: 9.0pt">&nbsp;</TD>
</TR>

<TR valign="top">
    <TD>&nbsp;</TD>
    <TD>(3)&nbsp;</TD>
    <TD align="left">
    In December 2003, the registrant issued a warrant to purchase
    807,427&nbsp;shares of its common stock at an exercise price of
    $10.50&nbsp;per share to Dell Ventures, L.P., an accredited
    investor, in connection with the registrant&#146;s entering into
    a software licensing agreement with Dell Products, L.P. as an
    original equipment manufacturer. The number of warrant shares
    and exercise price are subject to customary antidilution
    adjustments upon the occurrence of certain events. The issuance
    of the warrant was exempt from registration pursuant to
    Section&nbsp;4(2) of the Securities Act.</TD>
</TR>

<TR>
    <TD style="font-size: 9.0pt">&nbsp;</TD>
</TR>

<TR valign="top">
    <TD>&nbsp;</TD>
    <TD>(4)&nbsp;</TD>
    <TD align="left">
    On June&nbsp;15, 2006, the registrant issued 315,222 shares of
    its common stock upon the cashless exercise of the warrant held
    by Dell Ventures, L.P. that was issued to it in December 2003.
    The issuance of the shares was exempt from registration pursuant
    to Section&nbsp;4(2) of the Securities Act. The number of common
    shares issued on a cashless basis was equal to the vested
    warrants less the number of shares of common stock having an
    aggregate market price equal to the aggregate exercise price of
    the vested warrants. Market price was determined as the greater
    of (i)&nbsp;a product obtained by multiplying the Company&#146;s
    trailing 12-month revenues by six and (ii)&nbsp;the price of
    common stock sold in a qualified financing transaction within
    six months of the cashless exercise. During the year ended
    March&nbsp;31, 2004, CommVault recorded $1,696,000 as a non-cash
    reduction of revenue in connection with this transaction at the
    time the warrants were issued. In the three months ended
    June&nbsp;30, 2006, CommVault recorded $3,877 as an increase to
    common stock with a corresponding decrease to additional paid-in
    capital related to the common stock issued in connection with
    the cashless exercise and the preemptive rights held by the
    holders of CommVault&#146;s Series AA, BB and CC preferred stock.</TD>
</TR>

<TR>
    <TD style="font-size: 9.0pt">&nbsp;</TD>
</TR>

<TR valign="top">
    <TD>&nbsp;</TD>
    <TD>(5)&nbsp;</TD>
    <TD align="left">
    On June&nbsp;15, 2006, concurrently with the issuance of shares
    to Dell Ventures, L.P., the registrant issued 72,423&nbsp;shares
    of common stock to holders of its Series&nbsp;AA, BB and CC
    preferred stock in accordance with the preemptive rights of such
    holders. The registrant issued shares to each holder as if each
    holder held a warrant for the shares to which it was entitled
    pursuant to its preemptive rights and exercised such warrant on
    a cashless basis. The registrant issued such shares on the same
    terms that it issued shares to Dell Ventures, L.P. on the same
    date. The registrant was required to issue such shares to comply
    with the preemptive rights of holders of Series&nbsp;AA, BB and
    CC preferred stock, which such holders acquired when they
    acquired shares of Series&nbsp;AA, BB and CC preferred stock
    between April 2000 and September 2003. Under the terms of the
    Series&nbsp;AA, BB and CC preferred stock, the issuance of such
    shares was automatic and occurred without any action or election
    by the holders of Series&nbsp;AA, BB and CC preferred stock. The
    issuance of shares was exempt from registration pursuant to
    Section&nbsp;4(2) of the Securities Act.</TD>
</TR>

<TR>
    <TD style="font-size: 9.0pt">&nbsp;</TD>
</TR>

<TR valign="top">
    <TD>&nbsp;</TD>
    <TD>(6)&nbsp;</TD>
    <TD align="left">
    Concurrently with the closing of this offering, the registrant
    will issue 102,640&nbsp;shares of its common stock to Greg
    Reyes, Reyes Family Trust, Van Wagoner Capital Partners, L.P.
    and Van Wagoner Crossover Fund, L.P. in a private placement
    exempt from registration pursuant to Section&nbsp;4(2) of the
    Securities Act.</TD>
</TR>

<TR>
    <TD style="font-size: 9.0pt">&nbsp;</TD>
</TR>

<TR valign="top">
    <TD>&nbsp;</TD>
    <TD>(7)&nbsp;</TD>
    <TD align="left">
    From January&nbsp;1, 2003 to the date of this filing, the
    registrant granted options to purchase approximately
    5,710,450&nbsp;shares of common stock under the
    registrant&#146;s 1996 Stock Option Plan. Approximately
    91,565&nbsp;shares of common stock have been issued upon
    exercise of these options. All options were granted under
    Rule&nbsp;701 promulgated under the Securities Act or, in the
    case of certain options granted to N. Robert Hammer,
    Section&nbsp;4(2) of the Securities Act.</TD>
</TR>

</TABLE>

<DIV align="left" style="font-size: 10.0pt;color: #000000; background: #ffffff; margin-top: 9pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
There were no underwriters employed in connection with any of
the transactions set forth in this Item&nbsp;15. With respect to
each of the transactions described in paragraphs&nbsp;(2), (3),
(4), (6) and (7) (with respect to the certain options granted to
N. Robert Hammer), the recipients of securities represented
their intention to acquire the securities for investment only
and not with a view to any
</DIV>

<P align="center" style="font-size: 10.0pt;color: #000000; background: #ffffff;">II-3

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<DIV align="left" style="font-size: 10.0pt;color: #000000; background: #ffffff;">
distribution thereof. Appropriate legends were affixed to the
share certificates and other instruments issued in such
transactions. All recipients were given the opportunity to ask
questions and receive answers from representatives of the
registrant concerning the business and financial affairs of the
registrant. Each investor represented and acknowledged to
CommVault in writing that it had this opportunity. Each of the
recipients that were employees of the registrant had access to
such information through their employment with the registrant.
CommVault did not engage in any form of general solicitation or
general advertisement with respect to any of the transactions
set forth in this Item&nbsp;15.
</DIV>

<DIV style="margin-top: 15pt; margin-left: 0; margin-right: 0; margin-bottom: 0; color: #000000; background: #ffffff;"></DIV>

<TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10.0pt;color: #000000; background: #ffffff;">

<TR>
    <TD width="9%"></TD>
    <TD width="91%"></TD>
</TR>

<TR valign="top">
    <TD><B>Item&nbsp;16.</B></TD>
    <TD>
    <B><I>Exhibits and Financial Statement Schedules.</I></B></TD>
</TR>

</TABLE>

<DIV align="left" style="font-size: 10.0pt;color: #000000; background: #ffffff; margin-top: 9pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
(a)&nbsp;<I>Exhibits</I>
</DIV>

<DIV align="left" style="font-size: 10.0pt;color: #000000; background: #ffffff; margin-top: 9pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
See the exhibit index, which is incorporated herein by reference.
</DIV>

<DIV align="left" style="font-size: 10.0pt;color: #000000; background: #ffffff; margin-top: 9pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
(b)&nbsp;<I>Financial Statement Schedules</I>
</DIV>

<DIV align="left" style="font-size: 10.0pt;color: #000000; background: #ffffff; margin-top: 9pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
Schedule&nbsp;II&nbsp;&#151; Valuation and Qualifying Accounts
for the years ended March&nbsp;31, 2004, 2005 and 2006 (included
on page&nbsp;<FONT style="white-space: nowrap">F-29).</FONT>
</DIV>

<DIV style="margin-top: 15pt; margin-left: 0; margin-right: 0; margin-bottom: 0; color: #000000; background: #ffffff;"></DIV>

<TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10.0pt;color: #000000; background: #ffffff;">

<TR>
    <TD width="9%"></TD>
    <TD width="91%"></TD>
</TR>

<TR valign="top">
    <TD><B>Item&nbsp;17.</B></TD>
    <TD>
    <B><I>Undertakings.</I></B></TD>
</TR>

</TABLE>

<DIV align="left" style="font-size: 10.0pt;color: #000000; background: #ffffff; margin-top: 9pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
(a)&nbsp;The undersigned registrant hereby undertakes to provide
to the underwriters at the closing specified in the underwriting
agreements, certificates in such denominations and registered in
such names as required by the underwriters to permit prompt
delivery to each purchaser.
</DIV>

<DIV align="left" style="font-size: 10.0pt;color: #000000; background: #ffffff; margin-top: 9pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
(b)&nbsp;Insofar as indemnification for liabilities arising
under the Securities Act of 1933 may be permitted to directors,
officers and controlling persons of the registrant pursuant to
the foregoing provisions, or otherwise, the registrant has been
advised that in the opinion of the Securities and Exchange
Commission such indemnification is against public policy as
expressed in the Securities Act and is, therefore,
unenforceable. In the event that a claim for indemnification
against such liabilities (other than the payment by the
registrant of expenses incurred or paid by a director, officer
or controlling person of the registrant in the successful
defense of any action, suit or proceeding) is asserted by such
director, officer or controlling person in connection with the
securities being registered, the registrant will, unless in the
opinion of its counsel the matter has been settled by
controlling precedent, submit to a court of appropriate
jurisdiction the question whether such indemnification by it is
against public policy as expressed in the Securities Act and
will be governed by the final adjudication of such issue.
</DIV>

<DIV align="left" style="font-size: 10.0pt;color: #000000; background: #ffffff; margin-top: 9pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
(c)&nbsp;The undersigned registrant hereby undertakes that:
</DIV>

<DIV style="margin-top: 9pt; margin-left: 0; margin-right: 0; margin-bottom: 0; color: #000000; background: #ffffff;"></DIV>

<TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10.0pt;color: #000000; background: #ffffff;">

<TR>
    <TD width="3%"></TD>
    <TD width="97%"></TD>
</TR>

<TR valign="top">
    <TD>&nbsp;</TD>
    <TD align="left">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
    (1)&nbsp;For purposes of determining any liability under the
    Securities Act of 1933, the information omitted from the form of
    prospectus filed as part of this registration statement in
    reliance upon Rule&nbsp;430A and contained in a form of
    prospectus filed by the registrant pursuant to
    Rule&nbsp;424(b)(1) or (4)&nbsp;or 497(h) under the Securities
    Act shall be deemed to be part of this registration statement as
    of the time it was declared effective.</TD>
</TR>

<TR>
    <TD style="font-size: 6.0pt">&nbsp;</TD>
</TR>

<TR valign="top">
    <TD>&nbsp;</TD>
    <TD align="left">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
    (2)&nbsp;For the purpose of determining any liability under the
    Securities Act of 1933, each post-effective amendment that
    contains a form of prospectus shall be deemed to be a new
    registration statement relating to the securities offered
    therein, and the offering of such securities at that time shall
    be deemed to be the initial <I>bona fide </I>offering thereof.</TD>
</TR>

</TABLE>

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<DIV align="center" style="font-size: 10.0pt;color: #000000; background: #ffffff; margin-top: 18pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">
<B>SIGNATURES</B>
</DIV>

<DIV align="left"><FONT size="1">

</FONT></DIV>

<DIV align="left" style="font-size: 10.0pt;color: #000000; background: #ffffff; margin-top: 6pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
Pursuant to the requirements of the Securities Act of 1933, the
registrant has duly caused this registration statement to be
signed on its behalf by the undersigned, thereunto duly
authorized, in the city of Oceanport, State of New Jersey, on
September&nbsp;21, 2006.
</DIV>

<DIV align="left"><FONT size="1">

</FONT></DIV>

<DIV style="margin-top: 24pt; margin-left: 0; margin-right: 0; margin-bottom: 0; color: #000000; background: #ffffff;"></DIV>

<TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10.0pt;color: #000000; background: #ffffff;">

<TR>
    <TD width="40%"></TD>
    <TD width="60%"></TD>
</TR>

<TR valign="top">
    <TD>&nbsp;</TD>
    <TD align="left">
    COMMVAULT SYSTEMS, INC.</TD>
</TR>

</TABLE>

<DIV style="margin-top: 48pt; margin-left: 0; margin-right: 0; margin-bottom: 0; color: #000000; background: #ffffff;"></DIV>

<TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10.0pt;color: #000000; background: #ffffff;">

<TR>
    <TD width="40%"></TD>
    <TD width="2%"></TD>
    <TD width="58%"></TD>
</TR>

<TR valign="top">
    <TD>&nbsp;</TD>
    <TD>By:&nbsp;</TD>
    <TD align="left">
    /s/ N. ROBERT HAMMER</TD>
</TR>

</TABLE>

<TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 3.0pt;color: #000000; background: #ffffff;">

<TR>
    <TD width="40%"></TD>
    <TD width="60%"></TD>
</TR>

<TR valign="top">
    <TD>&nbsp;</TD>
    <TD align="left">
    <DIV style="border-top: 1pt solid black; font-size: 1pt; margin-top: 2pt" align="left">&nbsp;</DIV></TD>
</TR>

<TR valign="top"  style="font-size: 10.0pt;color: #000000; background: #ffffff;">
    <TD>&nbsp;</TD>
    <TD align="center">
    N. Robert Hammer</TD>
</TR>

<TR valign="top"  style="font-size: 10.0pt;color: #000000; background: #ffffff;">
    <TD>&nbsp;</TD>
    <TD align="center">
    <I>Chairman, President and Chief Executive Officer</I></TD>
</TR>

</TABLE>

<DIV align="center" style="font-size: 10.0pt;color: #000000; background: #ffffff; margin-top: 18pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">
<B>POWER OF ATTORNEY</B>
</DIV>

<DIV align="left"><FONT size="1">

</FONT></DIV>

<DIV align="left" style="font-size: 10.0pt;color: #000000; background: #ffffff; margin-top: 6pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
Pursuant to the requirements of the Securities Act of 1933, this
registration statement has been signed by the following persons
in the capacities indicated on September&nbsp;21, 2006.
</DIV>

<DIV align="left"><FONT size="1">

</FONT></DIV>

<CENTER>
<TABLE width="100%" align="center" cellspacing="0" cellpadding="0" border="0" style="font-size: 10.0pt; margin-top: 6pt; ">

<TR style="font-size: 1pt;">
    <TD width="5%">&nbsp;</TD>
    <TD width="3%">&nbsp;</TD>
    <TD width="40%">&nbsp;</TD>
    <TD width="3%">&nbsp;</TD>
    <TD width="49%">&nbsp;</TD>
</TR>


<TR style="font-size: 8.0pt;">
    <TD colspan="3" align="center" nowrap><B>Signature</B></TD>
    <TD>&nbsp;</TD>
    <TD align="center" nowrap><B>Title</B></TD>
</TR>

<TR valign="bottom" style="font-size: 1px">
    <TD colspan="3" align="center" nowrap style="border-top: 1pt solid #000000;">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD align="center" nowrap style="border-top: 1pt solid #000000;">&nbsp;</TD>
</TR>

<TR>
    <TD colspan="5">&nbsp;</TD>
</TR>

<TR>
    <TD colspan="3" align="center" valign="top">
    /s/ N. ROBERT HAMMER*<BR>
    <DIV style="font-size: 1pt; border-bottom: 1px solid #000000">&nbsp;</DIV>N.
    Robert Hammer</TD>
    <TD>&nbsp;</TD>
    <TD align="center" valign="top">
    Chairman, President and Chief Executive Officer</TD>
</TR>

<TR>
    <TD colspan="5">&nbsp;</TD>
</TR>

<TR>
    <TD colspan="3" align="center" valign="top">
    /s/ LOUIS F. MICELI*<BR>
    <DIV style="font-size: 1pt; border-bottom: 1px solid #000000">&nbsp;</DIV>Louis
    F. Miceli</TD>
    <TD>&nbsp;</TD>
    <TD align="center" valign="top">
    Vice President, Chief Financial Officer</TD>
</TR>

<TR>
    <TD colspan="5">&nbsp;</TD>
</TR>

<TR>
    <TD colspan="3" align="center" valign="top">
    /s/ BRIAN CAROLAN*<BR>
    <DIV style="font-size: 1pt; border-bottom: 1px solid #000000">&nbsp;</DIV>Brian
    Carolan</TD>
    <TD>&nbsp;</TD>
    <TD align="center" valign="top">
    Chief Accounting Officer</TD>
</TR>

<TR>
    <TD colspan="5">&nbsp;</TD>
</TR>

<TR>
    <TD colspan="3" align="center" valign="top">
    /s/ THOMAS BARRY*<BR>
    <DIV style="font-size: 1pt; border-bottom: 1px solid #000000">&nbsp;</DIV>Thomas
    Barry</TD>
    <TD>&nbsp;</TD>
    <TD align="center" valign="top">
    Director</TD>
</TR>

<TR>
    <TD colspan="5">&nbsp;</TD>
</TR>

<TR>
    <TD colspan="3" align="center" valign="top">
    /s/ FRANK J. FANZILLI, JR.*<BR>
    <DIV style="font-size: 1pt; border-bottom: 1px solid #000000">&nbsp;</DIV>Frank
    J. Fanzilli,&nbsp;Jr.</TD>
    <TD>&nbsp;</TD>
    <TD align="center" valign="top">
    Director</TD>
</TR>

<TR>
    <TD colspan="5">&nbsp;</TD>
</TR>

<TR>
    <TD colspan="3" align="center" valign="top">
    /s/ EDWARD A. JOHNSON*<BR>
    <DIV style="font-size: 1pt; border-bottom: 1px solid #000000">&nbsp;</DIV>Edward
    A. Johnson</TD>
    <TD>&nbsp;</TD>
    <TD align="center" valign="top">
    Director</TD>
</TR>

<TR>
    <TD colspan="5">&nbsp;</TD>
</TR>

<TR>
    <TD colspan="3" align="center" valign="top">
    /s/ ARMANDO GEDAY*<BR>
    <DIV style="font-size: 1pt; border-bottom: 1px solid #000000">&nbsp;</DIV>Armando
    Geday</TD>
    <TD>&nbsp;</TD>
    <TD align="center" valign="top">
    Director</TD>
</TR>

<TR>
    <TD colspan="5">&nbsp;</TD>
</TR>

<TR>
    <TD colspan="3" align="center" valign="top">
    /s/ KEITH GEESLIN*<BR>
    <DIV style="font-size: 1pt; border-bottom: 1px solid #000000">&nbsp;</DIV>Keith
    Geeslin</TD>
    <TD>&nbsp;</TD>
    <TD align="center" valign="top">
    Director</TD>
</TR>

<TR>
    <TD colspan="5">&nbsp;</TD>
</TR>

<TR>
    <TD colspan="3" align="center" valign="top">
    /s/ F. ROBERT KURIMSKY*<BR>
    <DIV style="font-size: 1pt; border-bottom: 1px solid #000000">&nbsp;</DIV>F.
    Robert Kurimsky</TD>
    <TD>&nbsp;</TD>
    <TD align="center" valign="top">
    Director</TD>
</TR>

<TR>
    <TD colspan="5">&nbsp;</TD>
</TR>

<TR>
    <TD colspan="3" align="center" valign="top">
    /s/ DANIEL PULVER*<BR>
    <DIV style="font-size: 1pt; border-bottom: 1px solid #000000">&nbsp;</DIV>Daniel
    Pulver</TD>
    <TD>&nbsp;</TD>
    <TD align="center" valign="top">
    Director</TD>
</TR>

</TABLE>
</CENTER>

<P align="center" style="font-size: 10.0pt;color: #000000; background: #ffffff;">II-5

<!-- PAGEBREAK -->
<P><HR noshade><P>
<H5 align="left" style="page-break-before:always">&nbsp;</H5><P>

<CENTER>
<TABLE width="100%" align="center" cellspacing="0" cellpadding="0" border="0" style="font-size: 10.0pt; ">

<TR style="font-size: 1pt;">
    <TD width="5%">&nbsp;</TD>
    <TD width="3%">&nbsp;</TD>
    <TD width="40%">&nbsp;</TD>
    <TD width="3%">&nbsp;</TD>
    <TD width="49%">&nbsp;</TD>
</TR>


<TR style="font-size: 8.0pt;">
    <TD colspan="3" align="center" nowrap><B>Signature</B></TD>
    <TD>&nbsp;</TD>
    <TD align="center" nowrap><B>Title</B></TD>
</TR>

<TR valign="bottom" style="font-size: 1px">
    <TD colspan="3" align="center" nowrap style="border-top: 1pt solid #000000;">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD align="center" nowrap style="border-top: 1pt solid #000000;">&nbsp;</TD>
</TR>

<TR>
    <TD colspan="5">&nbsp;</TD>
</TR>

<TR>
    <TD colspan="3" align="center" valign="top">
    /s/ GARY SMITH*<BR>
    <DIV style="font-size: 1pt; border-bottom: 1px solid #000000">&nbsp;</DIV>Gary
    Smith</TD>
    <TD>&nbsp;</TD>
    <TD align="center" valign="top">
    Director</TD>
</TR>

<TR>
    <TD colspan="5">&nbsp;</TD>
</TR>

<TR>
    <TD colspan="3" align="center" valign="top">
    /s/ DAVID F. WALKER*<BR>
    <DIV style="font-size: 1pt; border-bottom: 1px solid #000000">&nbsp;</DIV>David
    F. Walker</TD>
    <TD>&nbsp;</TD>
    <TD align="center" valign="top">
    Director</TD>
</TR>

<TR>
    <TD colspan="5">&nbsp;</TD>
</TR>

<TR>
    <TD colspan="3" align="center" valign="top">
    *By:&nbsp;/s/ N. ROBERT HAMMER<BR>
    <DIV style="font-size: 1pt; border-bottom: 1px solid #000000">&nbsp;</DIV>N.
    Robert Hammer<BR>
    Attorney-in-fact</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
</TR>

</TABLE>
</CENTER>

<P align="center" style="font-size: 10.0pt;color: #000000; background: #ffffff;">II-6

<!-- PAGEBREAK -->
<P><HR noshade><P>
<H5 align="left" style="page-break-before:always">&nbsp;</H5><P>

<DIV align="center" style="font-size: 10.0pt;color: #000000; background: #ffffff; margin-top: 18pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">
<B>INDEX TO EXHIBITS</B>
</DIV>

<DIV align="left"><FONT size="1">

</FONT></DIV>

<CENTER>
<TABLE width="100%" align="center" cellspacing="0" cellpadding="0" border="0" style="font-size: 10.0pt; margin-top: 6pt; ">

<TR style="font-size: 1pt;">
    <TD width="8%">&nbsp;</TD>
    <TD width="1%">&nbsp;</TD>
    <TD width="8%">&nbsp;</TD>
    <TD width="3%">&nbsp;</TD>
    <TD width="80%">&nbsp;</TD>
</TR>

<TR style="font-size: 8.0pt;">
    <TD colspan="3" align="center" nowrap><B>Exhibit</B></TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
</TR>

<TR style="font-size: 8.0pt;">
    <TD colspan="3" align="center" nowrap><B>No.</B></TD>
    <TD>&nbsp;</TD>
    <TD align="center" nowrap><B>Description</B></TD>
</TR>

<TR valign="bottom" style="font-size: 1px">
    <TD colspan="3" align="center" nowrap style="border-top: 1pt solid #000000;">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD align="center" nowrap style="border-top: 1pt solid #000000;">&nbsp;</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>1</TD>
    <TD align="left" valign="top" nowrap>.1*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    Form of Underwriting Agreement</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>3</TD>
    <TD align="left" valign="top" nowrap>.1*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    Amended and Restated Certificate of Incorporation of CommVault
    Systems, Inc., dated as of September&nbsp;14, 2006</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>3</TD>
    <TD align="left" valign="top" nowrap>.2*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    Form of Amended and Restated Certificate of Incorporation of
    CommVault Systems, Inc.</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>3</TD>
    <TD align="left" valign="top" nowrap>.3*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    Form of Amended and Restated Bylaws of CommVault Systems, Inc.</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>4</TD>
    <TD align="left" valign="top" nowrap>.1*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    Form of Common Stock Certificate</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>5</TD>
    <TD align="left" valign="top" nowrap>.1+</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    Opinion of Mayer, Brown, Rowe&nbsp;&#38; Maw LLP</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>9</TD>
    <TD align="left" valign="top" nowrap>.1*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    Form of Voting Trust Agreement</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>10</TD>
    <TD align="left" valign="top" nowrap>.1*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    Loan and Security Agreement, dated May&nbsp;2, 2006, between
    Silicon Valley Bank and CommVault Systems, Inc.</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>10</TD>
    <TD align="left" valign="top" nowrap>.2*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    CommVault Systems, Inc. 1996 Stock Option Plan, as amended</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>10</TD>
    <TD align="left" valign="top" nowrap>.3*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    Form of CommVault Systems, Inc. 2006 Long-Term Stock Incentive
    Plan</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>10</TD>
    <TD align="left" valign="top" nowrap>.4*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    Form of Non-Qualified Stock Option Agreement</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>10</TD>
    <TD align="left" valign="top" nowrap>.5*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    Employment Agreement, dated as of February&nbsp;1, 2004, between
    CommVault Systems, Inc. and N.&nbsp;Robert Hammer</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>10</TD>
    <TD align="left" valign="top" nowrap>.6*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    Form of Employment Agreement between CommVault Systems, Inc. and
    Alan G. Bunte and Louis F. Miceli</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>10</TD>
    <TD align="left" valign="top" nowrap>.7*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    Form of Corporate Change of Control Agreement between CommVault
    Systems, Inc. and Alan G. Bunte and Louis F. Miceli</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>10</TD>
    <TD align="left" valign="top" nowrap>.8*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    Form of Corporate Change of Control Agreement between CommVault
    Systems, Inc. and David West, Ron Miiller, Scott Mercer and
    Steven Rose</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>10</TD>
    <TD align="left" valign="top" nowrap>.9*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    Form of Indemnity Agreement between CommVault Systems, Inc. and
    each of its current officers and directors</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>10</TD>
    <TD align="left" valign="top" nowrap>.10*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    Amended and Restated Registration Rights Agreement, dated as of
    September&nbsp;2, 2003, by and among CommVault Systems, Inc. and
    the Series&nbsp;AA investors</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>10</TD>
    <TD align="left" valign="top" nowrap>.11*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    Amended and Restated Registration Rights Agreement, dated as of
    September&nbsp;2, 2003, by and among CommVault Systems, Inc. and
    the Series&nbsp;BB investors</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>10</TD>
    <TD align="left" valign="top" nowrap>.12*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    Amended and Restated Registration Rights Agreement, dated as of
    September&nbsp;2, 2003, by and among CommVault Systems, Inc. and
    the Series&nbsp;CC investors</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>10</TD>
    <TD align="left" valign="top" nowrap>.13*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    Form of Registration Rights Agreement by and between CommVault
    Systems, Inc. and certain holders of Series A, B, C, D and E
    preferred stock</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>10</TD>
    <TD align="left" valign="top" nowrap>.14*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    Purchase Agreement, dated April&nbsp;14, 2000, by and between
    Microsoft Corporation, certain investors and CommVault Systems,
    Inc.</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>10</TD>
    <TD align="left" valign="top" nowrap>.15*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    Purchase Agreement, dated November&nbsp;10, 2000, by and between
    EMC Investment Corporation, certain investors and CommVault
    Systems, Inc.</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>10</TD>
    <TD align="left" valign="top" nowrap>.16*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    Series&nbsp;CC Purchase Agreement, dated as of February&nbsp;14,
    2002, by and between funds and accounts managed by affiliates of
    Putnam Investments, LLC, certain investors and CommVault
    Systems, Inc.</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>10</TD>
    <TD align="left" valign="top" nowrap>.17*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    Series&nbsp;CC Purchase Agreement, dated as of September&nbsp;2,
    2003, by and between certain investors and CommVault Systems,
    Inc.</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>10</TD>
    <TD align="left" valign="top" nowrap>.18&#134;*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    Software License Agreement, dated December&nbsp;17, 2003, by and
    between Dell Products L.P. and CommVault Systems, Inc.</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>10</TD>
    <TD align="left" valign="top" nowrap>.19&#134;*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    Addendum One to the License and Distribution Agreement, dated
    May&nbsp;5, 2004, by and between Dell Products L.P. and
    CommVault Systems, Inc.</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>10</TD>
    <TD align="left" valign="top" nowrap>.20&#134;*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    Addendum Two to the License and Distribution Agreement, dated
    November 22, 2004, by and between Dell Products L.P. and
    CommVault Systems, Inc.</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>10</TD>
    <TD align="left" valign="top" nowrap>.21&#134;*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    Addendum Three to the License and Distribution Agreement, dated
    April 28, 2005, by and between Dell Products L.P. and CommVault
    Systems, Inc.</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>10</TD>
    <TD align="left" valign="top" nowrap>.22&#134;*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    Addendum Five to the License and Distribution Agreement, dated
    June&nbsp;6, 2006, by and between Dell Products L.P. and
    CommVault Systems, Inc.</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>10</TD>
    <TD align="left" valign="top" nowrap>.23&#134;*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    CommVault Systems Amended and Restated Reseller Agreement,
    effective as of April&nbsp;6, 2005, between CommVault Systems
    and Dell Inc.</TD>
</TR>

</TABLE>
</CENTER>

<DIV align="left"><FONT size="1">

</FONT></DIV>

<!-- PAGEBREAK -->
<P><HR noshade><P>
<H5 align="left" style="page-break-before:always">&nbsp;</H5><P>

<DIV align="left"><FONT size="1">

</FONT></DIV>

<CENTER>
<TABLE width="100%" align="center" cellspacing="0" cellpadding="0" border="0" style="font-size: 10.0pt; ">

<TR style="font-size: 1pt;">
    <TD width="8%">&nbsp;</TD>
    <TD width="1%">&nbsp;</TD>
    <TD width="8%">&nbsp;</TD>
    <TD width="3%">&nbsp;</TD>
    <TD width="80%">&nbsp;</TD>
</TR>

<TR style="font-size: 8.0pt;">
    <TD colspan="3" align="center" nowrap><B>Exhibit</B></TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
</TR>

<TR style="font-size: 8.0pt;">
    <TD colspan="3" align="center" nowrap><B>No.</B></TD>
    <TD>&nbsp;</TD>
    <TD align="center" nowrap><B>Description</B></TD>
</TR>

<TR valign="bottom" style="font-size: 1px">
    <TD colspan="3" align="center" nowrap style="border-top: 1pt solid #000000;">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD align="center" nowrap style="border-top: 1pt solid #000000;">&nbsp;</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>10</TD>
    <TD align="left" valign="top" nowrap>.24*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    Letter Agreement, dated February&nbsp;8, 2002, between the
    holders of Series A through E Preferred Stock and CommVault
    Systems, Inc.</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>10</TD>
    <TD align="left" valign="top" nowrap>.25*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    Stockholders Agreement, dated as of May&nbsp;22, 1996, among DLJ
    Merchant Banking Partners, L.P., DLJ International Partners,
    C.V., DLJ Offshore Partners, C.V., DLJ Merchant Banking Funding,
    Inc., DLJ Capital Corporation, Sprout Growth II, L.P., Sprout
    Capital VII, L.P., Sprout CEO Fund L.P., David H. Ireland,
    Scotty R. Neal, Robert Freiburghouse and CommVault Systems, Inc.</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>10</TD>
    <TD align="left" valign="top" nowrap>.26*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    Amendment to the Stockholders Agreement, dated July&nbsp;23,
    1998, among DLJ Merchant Banking Partners, L.P., DLJ
    International Partners C.V., DLJ Offshore Partners, C.V., DLJ
    Merchant Banking Funding, Inc., DLJ Capital Corporation, Sprout
    Growth II, L.P., Sprout Capital VII, L.P., Sprout CEO Fund L.P.,
    David H. Ireland, Scotty R. Neal, Robert Freiburghouse and
    CommVault Systems, Inc.</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>10</TD>
    <TD align="left" valign="top" nowrap>.27*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    Second Amendment to the Stockholders Agreement, dated
    November&nbsp;6, 2000, among DLJ Merchant Banking Partners,
    L.P., DLJ International Partners, C.V., DLJ Offshore Partners,
    C.V., DLJ Merchant Banking Funding, Inc., DLJ Capital
    Corporation, Sprout Growth II, L.P., Sprout Capital VII, L.P.,
    Sprout CEO Fund L.P., David H. Ireland, Scotty R. Neal, Robert
    Freiburghouse and CommVault Systems, Inc.</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>10</TD>
    <TD align="left" valign="top" nowrap>.28*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    Third Amendment to the Stockholders Agreement, dated
    February&nbsp;14, 2002, among DLJ Merchant Banking Partners,
    L.P., DLJ International Partners, C.V., DLJ Offshore Partners,
    C.V., DLJ Merchant Banking Funding, Inc., DLJ Capital
    Corporation, Sprout Growth II, L.P., Sprout Capital VII, L.P.,
    Sprout CEO Fund L.P., David H. Ireland, Scotty R. Neal, Robert
    Freiburghouse and CommVault Systems, Inc.</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>10</TD>
    <TD align="left" valign="top" nowrap>.29*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    Fourth Amendment to the Stockholders Agreement, dated
    September&nbsp;2, 2003, among DLJ Merchant Banking Partners,
    L.P., DLJ International Partners, C.V., DLJ Offshore Partners,
    C.V., DLJ Merchant Banking Funding, Inc., DLJ Capital
    Corporation, Sprout Growth II, L.P., Sprout Capital VII, L.P.,
    Sprout CEO Fund L.P. , David H. Ireland, Scotty R. Neal, Robert
    Freiburghouse and CommVault Systems, Inc.</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>10</TD>
    <TD align="left" valign="top" nowrap>.30*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    Fifth Amendment to the Stockholders Agreement, dated
    May&nbsp;22, 2006, by and among DLJ Merchant Banking Partners,
    L.P., DLJ International Partners, C.V., DLJ Offshore Partners,
    C.V., DLJ Merchant Banking Funding, Inc., DLJ Capital
    Corporation, DLJ First ESC, L.P., DLJ ESC II, L.P., Sprout
    Growth II, L.P., Sprout Capital VII, L.P., Sprout Capital IX,
    L.P., Sprout Entrepreneurs&#146; Fund, L.P., Sprout IX Plan
    Investors, L.P., Sprout CEO Fund L.P., Thomas J. Barry, Larry
    Cormier, Randy Fodero, Robert Freiburghouse, Bob Gailus, N.
    Robert Hammer, David H. Ireland, Lou Miceli, Tom Miller, Scotty
    R. Neal and CommVault Systems, Inc.</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>10</TD>
    <TD align="left" valign="top" nowrap>.31*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    Waiver Agreement, dated August&nbsp;28, 2006 between Putnam OTC
    and Emerging Growth Fund; TH&nbsp;Lee, Putnam Emerging
    Opportunities Portfolio; Putnam Technology Fund; Putnam World
    Trust&nbsp;II&nbsp;&#151; Putnam Emerging Information Sciences
    Fund; Putnam Discovery Growth Fund; EMC Investment Corporation;
    Van Wagoner Crossover Fund, L.P.; Van Wagoner Capital Partners,
    L.P.; Wheatley Partners&nbsp;III, L.P.; Wheatley Associates
    III,&nbsp;L.P.; Sprout IX Plan Investors, L.P.; Sprout
    Entrepreneurs Fund, L.P.; Sprout Capital IX, L.P.; DLJ Capital
    Corporation; Camelot Capital L.P.; Camelot Capital II&nbsp;L.P.;
    Camelot Offshore Fund Limited and CommVault Systems, Inc.</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>21</TD>
    <TD align="left" valign="top" nowrap>.1*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    List of Subsidiaries of CommVault Systems, Inc.</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>23</TD>
    <TD align="left" valign="top" nowrap>.1*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    Consent of Ernst&nbsp;&#38; Young LLP</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>23</TD>
    <TD align="left" valign="top" nowrap>.2+</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    Consent of Mayer, Brown, Rowe&nbsp;&#38; Maw LLP (included in
    Exhibit&nbsp;5.1)</TD>
</TR>

<TR>
    <TD align="right" valign="top">&nbsp;</TD>
    <TD align="right" valign="top" nowrap>24</TD>
    <TD align="left" valign="top" nowrap>.1*</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">
    Powers of Attorney (included on the signature page to the
    original registration statement)</TD>
</TR>

</TABLE>
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<DIV align="left"><FONT size="1">

</FONT></DIV>

<DIV align="left" style="font-size: 3.0pt;color: #000000; background: #ffffff; margin-top: 3pt; margin-left: 0; margin-right: 0; margin-bottom: 0; ">
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    <TD width="2%"></TD>
    <TD width="98%"></TD>
</TR>

<TR valign="top">
    <TD>*&nbsp;</TD>
    <TD align="left">
    Previously filed.</TD>
</TR>

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    <TD width="3%"></TD>
    <TD width="97%"></TD>
</TR>

<TR valign="top">
    <TD>+&nbsp;</TD>
    <TD align="left">
    Previously filed but updated version filed herewith.</TD>
</TR>

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<DIV style="margin-top: 3pt; margin-left: 0; margin-right: 0; margin-bottom: 0; color: #000000; background: #ffffff;"></DIV>

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    <TD width="3%"></TD>
    <TD width="97%"></TD>
</TR>

<TR valign="top">
    <TD>&#134;</TD>
    <TD align="left">
    Confidential treatment has been requested for portions of this
    document. Omitted portions have been filed separately with the
    SEC.</TD>
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<DOCUMENT>
<TYPE>EX-5.1
<SEQUENCE>2
<FILENAME>y24537a6exv5w1.txt
<DESCRIPTION>EX-5.1: OPINION OF MAYER, BROWN, ROWE & MAW LLP
<TEXT>
<PAGE>
                                                   [MAYER BROWN ROWE & MAW LOGO]

September 15, 2006                                  Mayer, Brown, Rowe & Maw LLP
                                                           71 South Wacker Drive
                                                   Chicago, Illinois  60606-4637

                                                         Main Tel (312) 782-0600
                                                         Main Fax (312) 701-7711
                                                          www.mayerbrownrowe.com


CommVault Systems, Inc.
2 Crescent Place
Oceanport, NJ 07757

Re:   Registration Statement on Form S-1
      File No. 333-132550

Ladies and Gentlemen:

      We have acted as counsel to CommVault Systems, Inc., a Delaware
corporation (the "Company"), in connection with the corporate proceedings taken
and to be taken relating to the public offering by the Company and by certain
stockholders of the Company of up to 12,777,778 shares of the Company's common
stock, $0.01 par value per share (the "Common Stock"). We have also participated
in the preparation of the Company's Registration Statement on Form S-1 (File No.
333-132550) (the "Registration Statement") filed with the Securities and
Exchange Commission (the "Commission") under the Securities Act of 1933, as
amended, relating to such Shares. The Company will offer and may sell up to
6,148,148 of such shares of Common Stock pursuant to the Registration Statement
(the "Primary Shares") and up to 6,629,630 of such shares of Common Stock will
be offered and may be sold by certain selling stockholders pursuant to the
Registration Statement (the "Secondary Shares"). Certain of the Secondary Shares
will be issued to the selling stockholders upon conversion of the outstanding
shares of the Company's preferred stock (the "Conversion"). In rendering the
opinion set forth below, we have examined such corporate and other records,
instruments, certificates and documents as we considered necessary to enable us
to express this opinion.

      Based upon the foregoing, we are of the opinion that:

      1. Upon the approval of the terms of the transaction and the underwriting
arrangements by the Pricing Committee of the Board of Directors of the Company
and the Filing of the Amended and Restated Certificate of Incorporation of the
Company with the Secretary of State of the State of Delaware in the manner
contemplated in the Registration Statement, the Primary Shares will have been
duly authorized and, when the Primary Shares are delivered in accordance with
the Underwriting Agreement in substantially the form filed as Exhibit 1.1 to the
Registration Statement, will be validly issued, fully paid and non-assessable.

<PAGE>

CommVault Systems, Inc.
September 15, 2006
Page 2

      2. The Secondary Shares which are currently outstanding were validly
issued, fully paid and non-assessable.

      3. Upon the filing of the Amended and Restated Certificate of
Incorporation of the Company with the Secretary of State of the State of
Delaware as contemplated in the Registration Statement, the Secondary Shares
which will be issued in the Conversion will be validly issued, fully paid and
non-assessable.

      We hereby consent to the filing of this opinion as Exhibit 5 to the
Registration Statement and to the reference to this firm under the caption
"Legal Matters" in the Prospectus constituting a part of the Registration
Statement.

                                      Very truly yours,


                                      /s/ Mayer, Brown, Rowe & Maw LLP

                                      Mayer, Brown, Rowe & Maw LLP
</TEXT>
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