Document:

<PAGE>

[***] INDICATES THAT TEXT HAS BEEN OMITTED WHICH IS THE SUBJECT OF A
CONFIDENTIAL TREATMENT REQUEST. THIS TEXT HAS BEEN FILED SEPARATELY WITH THE
SEC.

                                                                   EXHIBIT 10.20

                                  ADDENDUM TWO
                                     TO THE
                       LICENSE AND DISTRIBUTION AGREEMENT
                                     BETWEEN
                               DELL PRODUCTS L.P.
                                       AND
                             COMMVAULT SYSTEMS, INC.

This Addendum Two ("Addendum Two") to the Software License Agreement dated
December 17, 2003 (the "Agreement"), is entered into by and between DELL
PRODUCTS L.P. (HEREINAFTER "DELL") WITH ITS PRINCIPAL PLACE OF BUSINESS AT ONE
DELL WAY, ROUND ROCK, TEXAS 78682, AND COMMVAULT SYSTEMS, INC., (HEREINAFTER
"COMMVAULT") A DELAWARE CORPORATION HAVING A PRINCIPAL PLACE OF BUSINESS AT 2
CRESCENT PLACE, OCEANPORT, NEW JERSEY 07757 AND IS EFFECTIVE AS OF THE 30TH DAY
OF OCTOBER, 2004 (THE "EFFECTIVE DATE").

                                    RECITALS

WHEREAS, COMMVAULT and Dell entered into the Agreement through which COMMVAULT
granted Dell various rights to distribute certain COMMVAULT software products;

WHEREAS, the parties now desire to amend the Agreement.

NOW THEREFORE, in consideration of the mutual covenants and promises set forth
herein and for other good and valuable consideration, the receipt of which both
parties hereby acknowledge, Dell and COMMVAULT agree as follows:

Any capitalized terms defined in this Addendum are specific to this Addendum
only, and do not modify or change the meaning set forth in the Agreement. Unless
expressly defined in this Addendum, the capitalized terms in this Addendum are
as defined in the Agreement. The Agreement shall remain in full force and effect
except as supplemented and amended herein.

         1.       The Pricing Supplement to the Agreement is hereby replaced in
                  its entirety with the attached Exhibit B to this Addendum.

         2.       [***]. Dell shall coordinate with CommVault support to ensure
                  that customers who receive support and product updates are
                  eligible for such services. CommVault's MSRP for annual
                  maintenance contracts is [***] of product list price. Dell's
                  cost to CommVault is [***] of software cost and reflected in
                  the Exhibit B to this Addendum.

No other changes or modification are intended by this Addendum. All other terms
and conditions of the Agreement are in effect.

IN WITNESS WHEREOF, the parties have executed this Addendum by their duly
authorized representatives as of the date first set forth above.

<PAGE>

COMMVAULT SYSTEMS INC.                        DELL PRODUCTS L.P.

By:    /s/ David R. West                      By:    /s/ Joseph Kanicki
   -----------------------------------           -------------------------------
Name:  David R. West                          Name:  Joe Kanicki
     ---------------------------------             -----------------------------
Title: VP Business Development                Title: Sr. Manager -- WWSP
      --------------------------------              ----------------------------
Date:  11/15/2004                             Date:  11/22/2004
     ---------------------------------             -----------------------------

<PAGE>
                                    EXHIBIT B
                               PRICING SUPPLEMENT
                        TO THE SOFTWARE LICENSE AGREEMENT
                           BETWEEN DELL PRODUCTS L.P.
                           AND COMMVAULT SYSTEMS INC.

<TABLE>
<CAPTION>
                                                                                                              DELL SW   1 YR. UPDATE
SKU          SKU DESCRIPTION                                            [***]      [***]    MSRP    DISCOUNT  COST      PROTECTION
------       --------------------------------------------------------   -----      -----  --------- -------- ---------  -----------
<S>          <C>                                                        <C>        <C>    <C>       <C>      <C>        <C>
                                                                                   [***]
SKU1         CommServe                                                  [***]      [***]  $   [***]   [***]  $   [***]  $    [***]
SKU2         WINDOWS/LINUX/NETWARE Media Agent (SAN or LAN)
               with 1 OS IDA                                            [***]      [***]  $   [***]   [***]  $   [***]  $    [***]
SKU3         LAN Drive Pack with SLMS (per drive)                       [***]      [***]  $   [***]   [***]  $   [***]  $    [***]
SKU4         LAN Drive Pack with DDS and SLMS (per drive)               [***]      [***]  $   [***]   [***]  $   [***]  $    [***]
SKU5         DDO:  direct to disk option (per media agent)              [***]      [***]  $   [***]   [***]  $   [***]  $    [***]
SKU6         OS IDA WINDOWS/NETWARE/UNIX                                [***]      [***]  $   [***]   [***]  $   [***]  $    [***]
SKU7         Application IDA-WINDOWS                                    [***]      [***]  $   [***]   [***]  $   [***]  $    [***]
SKU8         OS IDA-UNIX                                                [***]      [***]  $   [***]   [***]  $   [***]  $    [***]
SKU9         Tier I UNIX Media Agent (SAN or LAN) with 1 OS IDA         [***]      [***]  $   [***]   [***]  $   [***]  $    [***]
SKU10        Tier II UNIX Media Agent (SAN or LAN) with 1 OS IDA        [***]      [***]  $   [***]   [***]  $   [***]  $    [***]
SKU11        Tier I Application IDA-UNIX                                [***]      [***]  $   [***]   [***]  $   [***]  $    [***]
SKU12        Tier II Application IDA-UNIX                               [***]      [***]  $   [***]   [***]  $   [***]  $    [***]
SKU13        Upgrade key to unlock GalaxyExpress to Galaxy                         [***]  $   [***]   [***]  $   [***]  $    [***]

SKU14        GalaxyExpress Server Suite includes:                       [***]      [***]  $   [***]   [***]  $   [***]  $    [***]
                GalaxyExpress (key code upgrade capability to Galaxy)
                1 Windows or Storage Server 2003 MediaAgent included
                Single tape drive support (no library support)
                5 FS Agents (can purchase more FS agents from list
                  above) for Windows, UNIX, Linux or Novell
                May purchase Windows Application Agents from above
                Max 10 total clients (agents)

SKU15        GalaxyExpress Automation Suite includes:                   [***]      [***]  $   [***]   [***]  $   [***]  $    [***]
                GalaxyExpress (key code upgrade capability to Galaxy)
                1 Windows, Storage Server 2003, Linux or Novell
                  MediaAgent included Media Agent supports a maximum
                  of one 6-drive library
                5 FS Agents (can purchase more FS agents from list
                  above) for Windows, UNIX, Linux or Novell
                Max 10 total clients (agents) inclusive of coupon for
                  1 Windows Application IDA
                (may purchase more Windows (only) application agents
                  from list above)

SKU16        Exchange Management Pak (EMP) (includes 25 CAL's)                            $   [***]   [***]  $   [***]  $    [***]

SKU17        Bundle of 25 Client Access Licenses for EMP                                  $   [***]   [***]  $   [***]  $    [***]

SKU18        Archiving and Compliance Pak (ACP) (includes 25 CAL's)                       $   [***]   [***]  $   [***]  $    [***]

SKU19        Bundle of 25 Client Access Licenses for ACP                                  $   [***]   [***]  $   [***]  $    [***]
</TABLE><PAGE>
[***] INDICATES THAT TEXT HAS BEEN OMITTED WHICH IS THE SUBJECT OF A
CONFIDENTIAL TREATMENT REQUEST. THIS TEXT HAS BEEN FILED SEPARATELY WITH THE
SEC.

                                                                   EXHIBIT 10.21

                                 ADDENDUM THREE
                                     TO THE
                       LICENSE AND DISTRIBUTION AGREEMENT
                                     BETWEEN
                               DELL PRODUCTS L.P.
                                       AND
                             COMMVAULT SYSTEMS, INC.

This Addendum ("Addendum") to the Software License Agreement dated December 17,
2003 (the "Agreement"), is entered into by and between Dell Products L.P.
(hereinafter "Dell") with its principal place of business at One Dell Way, Round
Rock, Texas 78682, and CommVault Systems, Inc., (hereinafter "Commvault" or
"Supplier"), a Delaware corporation having a principal place of business at 2
Crescent Place, Oceanport, New Jersey 07757 (hereinafter "Licensor") and is
effective as of the 1st day of May, 2005 (the "Effective Date").

                                    RECITALS

WHEREAS, COMMVAULT and Dell entered into the Agreement through which COMMVAULT
granted Dell various rights to distribute certain COMMVAULT software products;

WHEREAS, the parties now desire to amend the Agreement to provide that COMMVAULT
shall, for an additional fee, take on Level 2 Support obligations for new and
existing customers commencing on the Effective Date.

NOW, THEREFORE, in consideration of the mutual covenants and promises set forth
herein and for other good and valuable consideration, the receipt of which both
parties hereby acknowledge, Dell and COMMVAULT agree as follows:

Any capitalized terms define din this Addendum are specific to this Addendum
only, and do not modify or change the meaning set forth in the Agreement. Unless
expressly defined in this Addendum, the capitalized terms in this Addendum are
as defined in the Agreement. The Agreement shall remain in full force and effect
except as supplemented and amended herein.

1. Section 4.0 of Schedule C, Enterprise Support shall be modified by replacing
the existing first sentence in such section so that it reads as follows:

      [***]

2. Section 2 of Addendum Two to the License and Distribution Agreement, dated as
of October 30, 2004, which sets forth the price that Dell pays CommVault for
annual maintenance contracts, shall be amended in its entirety so that it reads
as follows:

      [***]. Dell shall coordinate with CommVault support to ensure that
      customers who receive support and product updates are eligible for such
      services. CommVault's MSRP

                                     Page 1
<PAGE>

      for annual maintenance contracts is [***] of product list price. Dell's
      cost to CommVault is [***] of software cost and reflected in the Exhibit B
      to this Addendum.

3. A new Section 3.5 shall be added to the Agreement that reads as follows:

      In addition to the report set forth in Section 3.4 above, Dell shall also
      submit [***] royalty reports to CommVault within [***] days after the end
      of each [***].

No other changes or modification are intended by this Addendum. All other terms
and conditions of the Agreement are in effect.

                                     Page 2
<PAGE>

IN WITNESS WHEREOF, the parties have executed this Addendum by their duly
authorized representatives as of the date first set forth above.

COMMVAULT SYSTEMS INC.                       DELL PRODUCTS L.P.

By:         /s/ David West                   By:         /s/ Joseph J. Kanicki
   -------------------------------------        ------------------------------

Name:       David West                       Name:       Joseph J. Kanicki
     -----------------------------------          ----------------------------

Title:      VP Business Development          Title:      Senior Manager
      ----------------------------------           ---------------------------

Date:       4-28-2005                        Date:       4-28-05
     -----------------------------------          ----------------------------

                                     Page 3
<PAGE>

                                    EXHIBIT B
                               PRICING SUPPLEMENT
                        TO THE SOFTWARE LICENSE AGREEMENT
                           BETWEEN DELL PRODUCTS L.P.
                           AND COMMVAULT SYSTEMS INC.

<TABLE>
<CAPTION>
                                                                                                                 1 YR.
 DELL                                                                                        SW      DELL SW    UPDATE     TOTAL
  SKU                         SKU DESCRIPTION                           [***]     [***]     MSRP      COST    PROTECTION   COGS
------  -------------------------------------------------------------   -----     -----    ------    -------  ----------   -----
<S>     <C>                                                             <C>       <C>      <C>       <C>      <C>          <C>
 SKU 1  CommServe                                                       [***]     [***]    $[***]    [***]       [***]     [***]

 SKU 2  WINDOWS UNIX/NETWARE Media Agent (SAN or LAN) with 1 OS IDA     [***]     [***]    $[***]    [***]       [***]     [***]

 SKU 3  LAN Drive Pack with SLMS (per drive)                            [***]     [***]    $[***]    [***]       [***]     [***]

 SKU 4  SAN Drive Pack with DDS and SLMS (per drive)                    [***]     [***]    $[***]    [***]       [***]     [***]

 SKU 5  OS IDA-WINDOWS/NETWARE/LINUX                                    [***]     [***]    $[***]    [***]       [***]     [***]

 SKU 6  Application IDA-WINDOWS                                         [***]     [***]    $[***]    [***]       [***]     [***]

 SKU 7  OS IDA-UNIX                                                     [***]     [***]    $[***]    [***]       [***]     [***]

 SKU 8  Tier I UNIX Media Agent (SAN  or LAN) with 1 OS IDA             [***]     [***]    $[***]    [***]       [***]     [***]

 SKU 9  Tier II UNIX Media Agent (SAN  or LAN) with 1 OS IDA            [***]     [***]    $[***]    [***]       [***]     [***]

SKU 10  Tier I Application IDA-UNIX                                     [***]     [***]    $[***]    [***]       [***]     [***]

SKU 11  Tier II Application IDA-UNIX                                    [***]     [***]    $[***]    [***]       [***]     [***]

SKU 12  Upgrade key to unlock GalaxyExpress to Galaxy                   [***]     [***]    $[***]    [***]       [***]     [***]

SKU 13  GalaxyExpress Server Suite includes:                            [***]     [***]    $[***]    [***]       [***]     [***]
             Galaxy Express (key code upgrade capability to Galaxy)
             1 Windows or Storage Server 2003 Media Agent included
             Single tape drive support (no library support)
             5 FS Agents (can purchase more FS agents from list above)
               for Windows, UNIX, Linux or Novell
             May purchase Windows Application Agents from above
             Max 10 total clients (agents)

SKU 14  Galaxy Express Server PRO Suite includes:                       [***]     [***]    $[***]    [***]       [***]     [***]
             GalaxyExpress (key code upgrade capability to Galaxy)
             1 Windows, Storage Server 2003, Linux or Novell Media
               Agent included
             Media Agent supports a maximum of one 6-drive library
             5 FS Agents (can purchase more FS Agents from list
               above) for Windows, UNIX, Linux or Novell
             Max 10 total clients (agents) inclusive of coupon for
               1 Windows Application IDA

             (may purchase more Windows (only) application agents
               from list above)

SKU 15  Exchange Management Pak (EMP) (includes 25 CAL's)                                  $[***]    [***]       [***]     [***]

SKU 16  Bundle of 25 Client Access Libraries for EMP                                       $[***]    [***]       [***]     [***]
</TABLE>

                                     Page 4

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00110-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00110-of-00352.parquet"}]]