Document:

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                                                                   EXHIBIT 10.26

                                    AMENDMENT
                                       TO
                           THE STOCKHOLDERS AGREEMENT

This Amendment to The Stockholders Agreement dated as of May 22, 1996 entered
into 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. (the "Amendment") shall be effective as of the signature date
below.

WHEREAS, CommVault Systems, Inc., (the "Issuer") has entered into a
Stockholder's Agreement dated as of May 22, 1006 (the "Agreement") along with
the parties named above;

WHEREAS, the Issuer desires to amend the terms of said Agreement;

WHEREAS, Issuer has secured the proper approvals to amend the terms of said
Agreement;

NOW, THEREFORE, the Agreement shall be amended, pursuant to its terms, as
follows:

Section 2.1 shall be modified to read as follows:

(i)  General. (a) Until the earlier of (i) the fifth anniversary of the date of
     this Agreement or (ii) six (6) months or the date as otherwise set forth by
     the Underwriters from the consummation of an Initial Public Offering, the
     earlier of such dates, (the "Restriction Termination Date"), no stockholder
     may, directly or indirectly, sell, assign, transfer, grant a participation
     in, pledge or otherwise dispose of ("transfer") any Stock (or solicit any
     offers to buy or otherwise acquire, to take a pledge of, any of its Stock)
     except transfers permitted by Section 2.3.

Section 6.6 shall be modified to read as follows:

     If to Management or the Issuer, to:
          CommVault Systems, Inc.
          2 Crescent Place, Building B
          P.O. Box 900
          Oceanport, New Jersey 07757-0900
          Attention: CEO
          Fax: 732-870-4512

All capitalized terms shall have the same meaning as assigned to such term in
the Agreement. All terms and conditions of the Agreement which are not
specifically amended herein shall remain in full force and effect. This
Amendment shall be binding upon and inure to the benefit of the parties to the
Agreement.

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By signing below, the Issuer acknowledges that all approvals necessary relating
to the execution of this Agreement have been obtained and are in full force and
effect.

CommVault Systems, Inc.

/s/ Scotty R. Neal
----------------------------------------
Scotty R. Neal
Title: President
Date: July 23, 1998

                                        2<PAGE>

                                                                   EXHIBIT 10.27

                                    AMENDMENT
                                       TO
                           THE STOCKHOLDERS' AGREEMENT

     This Second Amendment (this "Amendment") to The Stockholders' Agreement
dated as of May 22, 1996, as amended, entered into 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. (collectively, the "DLJ
Entities"), David H. Ireland, Scotty R. Neal, Robert Freiburghouse and CommVault
Systems, Inc. (the "Issuer") shall be effective as of the signature date below.

     WHEREAS, the Issuer has entered into a Stockholders' Agreement dated as of
May 22, 1996, as amended (the "Agreement"), along with the DLJ Entities and the
other parties thereto; and

     WHEREAS, the Issuer and the DLJ Parties desire to amend the terms of the
Agreement;

     NOW THEREFORE, the Agreement shall be amended, pursuant to the terms, as
follows:

     1. The carryover paragraph directly after Section 4.1(a)(ii) shall be
     amended to replace the word "three" directly before "Demand Registrations"
     in the first proviso, with the word "six", with the intent that the DLJ
     Entities shall have the right to request up to six Demand Registrations
     pursuant to Section 4.1.

     2. Section 4.1(d) shall be modified to read as follows:

     "    (d) If a Demand Registration involves an Underwritten Public Offering
     and the managing underwriter shall advise the Issuer and the Selling
     Stockholders in writing that, in its opinion, the number of shares of
     Common Stock requested to be included in such registration (including
     Common Stock which the Issuer proposes to be included which is not
     Registrable Stock or any other securities of other parties with piggyback
     registration rights) exceeds the largest number of Stock which can be sold
     in an orderly manner within a price range acceptable to the Selling
     Stockholders (the "MAXIMUM OFFERING SIZE"), the Issuer will include such
     registration, in the priority listed below, up to the Maximum Offering
     Size:

          (i) first, the Registrable Stock requested be included in such
          registration by the Holders of Registrable Stock requesting such
          registration and any securities requested to be included therein by
          any other holder pursuant to such holder's piggyback rights granted
          under the Registration Rights Agreement, dated April 14, 2000 (the
          "PRIOR HOLDERS"), pro rata on the basis of the number of shares of
          Registrable Stock and other securities requested for inclusion in such
          registration by each such Holder or Prior Holder;

          (ii) second, any securities requested to be included therein by any
          other holders pursuant to such holders' piggyback rights, if any, pro
          rata on the basis of the

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          number of shares of such securities requested for inclusion in such
          registration by each such holder; and

          (iii) third, the Common Stock proposed to be registered by the Issuer,
          if any."

     3. Section 4.2(b) shall be modified to read as follows:

     "    (b) If a registration pursuant to this Section 4.2 involves a primary
     Underwritten Public Offering on behalf of the Issuer and the managing
     underwriter advises the Issuer that in its opinion, the numbers of shares
     of Common Stock requested to be included exceeds the Maximum Offering Size,
     the Issuer will include in such registration, in the following priority, up
     to the Maximum Offering Size:

          (i) first, the Common Stock proposed to be registered by the Issuer;

          (ii) second, the securities requested to be included in such
          registration by the Prior Holders pro rata on the basis of the number
          of shares of securities requested for inclusion in such registration
          by each such Prior Holder; and

          (iii) third, the Registrable Stock requested be included in such
          registration among the Holders of Registrable Stock requesting such
          registration and any securities requested to be included therein by
          any other holder pursuant to such holder's piggyback rights, if any,
          pro rata on the basis of the number of shares of Registrable Stock and
          other securities requested for inclusion in such registration by each
          such Holder or holder."

          (c) If a registration pursuant to this Section 4.2 involves a
     secondary Underwritten Public Offering requested by holders of the Issuer's
     securities other than the Holders of Registrable Stock and the managing
     underwriter advises the Issuer that in its view, the numbers of shares of
     Common Stock requested to be included exceeds the Maximum Offering Size,
     the Issuer will include in such registration, in the following priority, up
     to the Maximum Offering Size:

          (i) first, the securities requested be included in such registration
          by the holders requesting such registration and the securities of the
          Prior Holders requested to be included therein, if any, pro rata on
          the basis of the number of shares of such securities requested for
          inclusion in such registration by each such holder or Prior Holder;

          (ii) second, the Registrable Stock requested be included in such
          registration by the Holders of Registrable Stock and any securities
          requested to be included therein by any other holder pursuant to such
          holder's piggyback rights, if any, pro rata on the basis of the number
          of shares of Registrable Stock and other securities requested for
          inclusion in such registration by each such Holder or holder;

          (iii) third, the Common Stock proposed to be registered by the Issuer,
          if any.

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     4. All capitalized terms shall have the same meaning as assigned to such
     term in the Agreement. All terms and conditions of the Agreement which are
     not specifically amended herein shall remain in full force and effect. This
     Amendment shall be binding upon and inure to the benefit of the parties to
     the Agreement.

     5. This Amendment has been approved by the Board and the signatories hereto
     represent holders of at least 85% of the Fully Diluted Common Stock held by
     parites to the Agreement, in compliance with Section 6.4 of the Agreement.

                            [Signature Page Follows]

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     IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be
duly executed as of this 6th day of November, 2000

                                        DLJ MERCHANT BANKING PARTNERS, L.P.

                                        By: DLJ Merchant Banking, Inc.
                                            Managing General Partner

                                        By: /s/ Ivy Dodes
                                            ------------------------------------
                                        Name: Ivy Dodes
                                              Principal

                                        DLJ INTERNATIONAL PARTNERS, C.V.

                                        By: DLJ Merchant Banking, Inc.
                                            Advisory General Partner

                                        By: /s/ Ivy Dodes
                                            ------------------------------------
                                        Name: Ivy Dodes
                                              Principal

                                        DLJ OFFSHORE PARTNERS, C.V.

                                        By: DLJ Merchant Banking, Inc.
                                            Advisory General Partner

                                        By: /s/ Ivy Dodes
                                            ------------------------------------
                                        Name: Ivy Dodes
                                              Principal

                                        DLJ MERCHANT BANKING FUNDING, INC.

                                        By: /s/ Ivy Dodes
                                            ------------------------------------
                                        Name: Ivy Dodes
                                              Vice President

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                                        DLJ CAPITAL CORPORATION

                                        By: /s/ Arthur S. Zuckerman
                                            ------------------------------------
                                        Name: Arthur S. Zuckerman
                                              Authorized Signatory

                                        SPROUT GROWTH II, L.P.

                                        By: DLJ Capital Corporation,
                                            Managing General Partner

                                        By: /s/ Arthur S. Zuckerman
                                            ------------------------------------
                                        Name:
                                              ----------------------------------
                                        Title:
                                               ---------------------------------

                                        SPROUT CAPITAL VII, L.P.

                                        By: DLJ Capital Corporation,
                                            Managing General Partner

                                        By: /s/ Arthur S. Zuckerman
                                            ------------------------------------
                                        Name: Arthur S. Zuckerman
                                              Authorized Signatory

                                        SPROUT CEO FUND, L.P.

                                        By: DLJ Capital Corporation,
                                            Managing General Partner

                                        By: /s/ Arthur S. Zuckerman
                                            ------------------------------------
                                        Name: Arthur S. Zuckerman
                                              Authorized Signatory

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                                        DLJ FIRST ESC, L.P.

                                        By: DLJ LBO Management Corporation, its
                                            General Partner

                                        By: /s/ Ivy Dodes
                                            ------------------------------------
                                        Name: Ivy Dodes
                                              Principal

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                                        COMMVAULT SYSTEMS, INC.

                                        By: /s/ N. Robert Hammer
                                            ------------------------------------
                                        Name: N. Robert Hammer
                                        Title: President

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