Document:

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                                                                    EXHIBIT 10.4

                             COMMVAULT SYSTEMS, INC.
                      NON-QUALIFIED STOCK OPTION AGREEMENT

This Non-Qualified Stock Option Agreement (the "Agreement") dated, is made by
and between CommVault Systems, Inc., a Delaware corporation (the
"Company") and (the "Optionee").

By signing below, the Optionee acknowledges that he or she has read, understands
and agrees to be bound by all terms and conditions of this Agreement set forth
herein and attached hereto, including the Grant Notice, (together the
"Agreement").

CommVault Systems, Inc.

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Signature                                      Optionee's Signature
N. Robert Hammer
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Name
Chief Executive Officer
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Title

PLEASE SIGN AND RETURN THIS DOCUMENT IN ITS ENTIRETY TO
CHRISTINE HALPER - FINANCE.
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                NOTICE OF GRANT OF STOCK OPTION ("GRANT NOTICE")

Notice is hereby given to the Optionee, as identified above, of the following
option grant (the "Options") to purchase shares of the Common Stock of CommVault
Systems, Inc.

Grant Date:

Vesting Commencement Date:

Exercise Price:

Number of Options:

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Expiration Date:

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Commencement of Exercisability:

(a)      Subject to subsection (b), the Options shall become exercisable in
         cumulative installments as follows: (i) The first installment shall
         consist of shares and shall become exercisable on the first day
         following the first anniversary of the Vesting Commencement Date
         thereafter. (ii) An installment consisting of shares shall become
         exercisable on the first day following each quarterly anniversary of
         the Vesting Commencement Date thereafter.

(b)      Notwithstanding the foregoing, no portion of the Option, which is
         unexercisable upon the Optionee's Termination of Employment shall
         thereafter become exercisable.

(c)      Optionee understands and agrees that the Options are granted subject to
         and in accordance with the terms of the CommVault Systems, Inc. 1996
         Stock Option Plan (the "Plan") and any amendments thereto. Optionee
         understands that any shares of Common Stock purchased under the Options
         will be subject to the terms set forth in the Stockholders Agreement
         and any amendments thereto, which may be reviewed at the Company's
         offices. Optionee hereby acknowledges receipt of a copy of the Plan.

TRANSFER RESTRICTIONS. OPTIONEE HEREBY AGREES THAT ALL SHARES OF COMMON STOCK
ACQUIRED UPON THE EXERCISE OF THE OPTIONS SHALL BE SUBJECT TO CERTAIN TRANSFER
RESTRICTIONS AND RIGHTS OF FIRST REFUSAL EXERCISABLE BY THE COMPANY AND ITS
ASSIGNS. THE TERMS OF SUCH RIGHTS AND RESTRICTIONS ARE SPECIFIED IN THE
STOCKHOLDERS AGREEMENT, AVAILABLE FOR REVIEW AT THE COMPANY'S OFFICES.

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                             COMMVAULT SYSTEMS, INC.
                      NON-QUALIFIED STOCK OPTION AGREEMENT

         WHEREAS, the Company has adopted the CommVault Systems, Inc. 1996 Stock
Option Plan (the "Plan");

         WHEREAS, the Optionee is an employee of Company, or other Participant
as defined in the Plan;

         WHEREAS, the Options granted pursuant to this Agreement and the shares
of Common Stock issued upon exercise of the Options are subject to all of the
terms and provisions of the Plan and the Stockholders Agreement. In the event of
any conflict between this Agreement and the Plan, the terms of the Plan shall
control, and in the event of any conflict between this Agreement or the Plan and
the Stockholders Agreement, the terms of the Stockholders Agreement shall
control.

         NOW, THEREFORE, in consideration of the mutual covenants herein
contained and other good and valuable consideration, receipt of which is hereby
acknowledged, the Company and the Optionee do hereby agree to the terms and
conditions of this Agreement.

                                   DEFINITIONS

The following terms shall have the meanings specified below unless the context
clearly indicates to the contrary. The singular pronoun shall include the
plural, where the context so indicates. Other capitalized terms not defined in
this Agreement shall have the meanings specified in the Plan.

1. "BOARD" shall mean the Board of Directors of the Company.

2. "COMMITTEE" shall mean the Compensation Committee of the Board; provided,
however, that in the event no such Committee is elected, the Board shall have
all duties and powers reserved to the Committee, and the term "Committee" as
used herein shall refer to the Board.

3. "COMMON STOCK" shall mean the common stock, par value $0.01 per share, of the
Company.

4. "EXCHANGE ACT" shall mean the Securities Exchange Act of 1934, as amended.

5. "FAIR MARKET VALUE" of a share of Common Stock as of a given date shall be

         (a) the fair market value of a share of Common Stock as established by
the Committee acting in good faith, or

         (b) if Common Stock is publicly traded on an exchange or quoted on
NASDAQ or any over-the-counter system, the average over a period of 21 days
consisting of the date as of which the Fair Market Value is being determined and
the 20 consecutive trading days prior to such date of the mean between the
closing prices of the sales of such Common Stock as of such dates on all
national securities exchanges on which such securities may at the time be
listed, or if there have been no sales on any such exchange on any such dates,

         (c) the mean between the highest bid and lowest asked prices on all
such exchanges at the close of business on such dates, or, if Common Stock is
not listed on an exchange but is quoted in the NASDAQ system, the mean between
the representative bid and asked prices quoted

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in the NASDAQ System as of 4:00 P.M., New York time on such dates, or, if Common
Stock is not quoted in the NASDAQ System,

         (d) the mean between the highest bid and lowest asked prices on such
dates in the domestic over-the-counter market as reported by the National
Quotation Bureau Incorporated, or any similar successor organization.

6. "GRANT NOTICE" shall mean the Notice of Grant of Stock Option accompanying
this Agreement, pursuant to which the Optionee has been informed of the terms of
the Options evidenced hereby.

7. "OPTIONS" shall mean the non-qualified stock options to purchase Common Stock
granted to the Optionee pursuant to the Plan and the Grant Notice.

8. "PARENT CORPORATION" shall mean any corporation in an unbroken chain of
corporations ending with the Company if each of the corporations other than the
Company then owns stock possessing 50% or more of the total combined voting
power of all classes of stock in one of the other corporations in such chain.

9. "PLAN" shall mean that certain CommVault Systems, Inc. 1996 Stock Option
Plan, as amended.

10. "QDRO" shall mean a qualified domestic relations order as defined by the
Internal Revenue Code of 1986, as amended, or Title I of the Employee Retirement
Income Security Act of 1974, as amended, or the regulations and rules
thereunder.

11. "RULE 16B-3" shall mean that certain Rule 16b-3 under the Exchange Act, as
such Rule may be amended from time to time.

12. "SECURITIES ACT" shall mean the Securities Act of 1933, as amended.

13. "STOCKHOLDERS AGREEMENT" shall mean that certain Stockholders Agreement
dated as of May 22, 1996, as amended, by and among the Company and the other
stockholders of the Company that are or may from time to time become parties
thereto.

14. "SUBSIDIARY" shall mean any corporation in an unbroken chain of corporations
beginning with the Company if each such corporation, other than the last
corporation in the unbroken chain, then owns stock possessing 50% or more of the
total combined voting power of all classes of stock in one of the other
corporations in such chain.

15. "TERMINATION OF EMPLOYMENT" shall mean the time when the employee-employer
relationship between the Optionee and the Company or any Parent Corporation or
Subsidiary is terminated for any reason, with or without good cause, including,
but not by way of limitation, a termination by resignation, discharge, death,
disability or retirement; but excluding (a) a termination where there is a
simultaneous reemployment or continuing employment of the Optionee by the
Company or any Parent Corporation or Subsidiary, (b) at the discretion of the
Committee, a termination which results in a temporary severance of the
employee-employer relationship, and (c) at the discretion of the Committee, a
termination which is followed by the simultaneous establishment of a consulting
relationship by the Company or any Parent Corporation or Subsidiary with the
Optionee. The Committee, in its discretion, shall determine the effect of all
matters and questions relating to Termination of Employment, including, but not
by way of limitation, the question of whether a Termination of Employment
resulted from a discharge for good cause, and all questions of whether a
particular leave of absence constitutes Terminations of Employment.
Notwithstanding any other provision of this Agreement or the Plan, the Company
or any Parent Corporation or Subsidiary has an absolute and unrestricted right
to terminate the Optionee's employment at any time for any reason whatsoever,
with or without good cause, except to the extent expressly provided otherwise in
a written employment agreement between the Optionee and the Company (or Parent
Corporation or Subsidiary).

                           ARTICLE I: GRANT OF OPTIONS

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1.1 GRANT OF OPTIONS. In consideration of the Optionee's promises set forth in
Section 1.2, and for other good and valuable consideration, on the date hereof
the Company irrevocably grants to the Optionee, subject to the terms and
conditions set forth in this Agreement and the Plan, the number of Options
specified in the Grant Notice, each with respect to one share of Common Stock,
subject to adjustment as provided in the Plan and herein.

1.2  CONSIDERATION TO THE COMPANY

         1.2.1 FAITHFUL SERVICES. In consideration of the granting of the
Options the Optionee agrees to render faithful and efficient services to the
Company or a Parent Corporation or a Subsidiary of the Company, with such duties
and responsibilities as such employer shall from time to time prescribe.

         1.2.2 NON-COMPETITION. In consideration of the granting of the Options
the Optionee agrees that Optionee WILL NOT IN ANY MANNER OR CAPACITY, DIRECTLY
OR INDIRECTLY, COMPETE WITH COMPANY in any business presently or hereafter
engaged in by Company during the period of his or her employment and for a
period of ONE (1) YEAR from Optionee's Termination of Employment with Company.

         1.2.3 NON-SOLICITATION. In consideration of the granting of the Options
the Optionee agrees that Optionee will not in any manner or capacity, directly
or indirectly, solicit or attempt to solicit for employment, whether full time,
part time or on a consultant basis, any current or future employee of Company
for a period of 1 year.

         1.2.4 DIVERSION OF BUSINESS. In consideration of the granting of the
Options the Optionee agrees that Optionee will not in any manner or capacity,
directly or indirectly, divert or attempt to divert from Company, through any
means whatsoever, any business or customers of Company.

         1.2.5 ADEQUATE AND LEGITIMATE PROTECTION OF COMPANY/INJUNCTIVE RELIEF.
Optionee recognizes that the foregoing obligations and limitations are
reasonable for the legitimate and adequate protection of the Company in
consideration of the Options herein granted. The parties acknowledge that the
injury that Company will suffer in the event of a breach by Optionee of this
Section 1.2 cannot be compensated by monetary damages alone, and Optionee
therefore agrees that Company, in addition to and without limiting any other
remedies or rights that it may have either under this Agreement or otherwise,
shall have the right to obtain an injunction against Optionee from any court of
competent jurisdiction, enjoining such breach.

         1.2.6 EMPLOYMENT AT WILL. Nothing in this Agreement shall confer upon
the Optionee any right to continue in the employ of the Company, any Parent
Corporation or any Subsidiary or shall interfere with or restrict in any way the
rights of the Company, any Parent Corporation or any Subsidiary of the Company,
which are hereby expressly reserved, to discharge the Optionee at any time for
any reason whatsoever, with or without good cause.

 1.3 ADJUSTMENTS IN OPTIONS. In the event that the outstanding shares of the
stock subject to the Options are changed into or exchanged for a different
number or kind of shares of the Company or other securities of the Company by
reason of merger, consolidation, recapitalization, reclassification, stock
split, stock dividend or combination of shares, the Committee shall make an
appropriate and equitable adjustment in the number and kind of shares as to
which the Options, or portions thereof then unexercised, shall be exercisable,
to the end that after such

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event the Optionee's proportionate interest shall be maintained as before the
occurrence of such event. Such adjustment in the Options shall be made without
change in the total price applicable to the unexercised portion of the Options
(except for any change in the aggregate price resulting from rounding-off of
share quantities or prices) and with any necessary corresponding adjustment in
the exercise price per share. Any such adjustment made by the Committee shall be
final and binding upon the Optionee, the Company and all other interested
persons.

1.4 EXERCISABILITY. Options shall become exercisable in one or more installments
as specified in the Grant Notice. Such installments shall accumulate and each
such installment which becomes exercisable shall remain exercisable until it
becomes unexercisable under Section 1.5.

1.5 EXPIRATION OF OPTIONS. The Options may not be exercised to any extent by
anyone after the first to occur of the following events: (a) The tenth (10th)
anniversary of the date of this Agreement; or, (b) The thirtieth (30th) day
following the Optionee's Termination of Employment for any reason; or, (c) The
effective date of the occurrence of a transaction or event described in Section
3.3 in connection with which the Committee provides, by action taken prior to
the occurrence of such transaction or event, that the Options shall not be
exercisable after such transaction or event.

                         ARTICLE II: EXERCISE OF OPTIONS

2.1 PERSON ELIGIBLE TO EXERCISE. During the lifetime of the Optionee, only he or
she may exercise the Options or any portion thereof, unless it has been disposed
of pursuant to a QDRO. After the death of the Optionee, any exercisable portion
of the Options may, prior to the time when the Options (or portion thereof)
become unexercisable under Section 1.5, be exercised by his or her personal
representative or by any person empowered to do so under the Optionee's will or
under the then applicable laws of descent and distribution.

2.2 PARTIAL EXERCISE. Exercisable Options may be exercised in whole or in part
at any time prior to the time when the Options or portion thereof become
unexercisable under Section 1.5; provided, however, that each partial exercise
shall be for not less than the smallest exercisable installment set forth in the
Grant Notice, and shall be for whole shares only.

2.3 MANNER OF EXERCISE. The Options, or any exercisable portion thereof, shall
be deemed exercised upon delivery of all of the following to the Secretary of
the Company or his or her office prior to the Option becoming unexercisable
under Section 1.5:

         (a) A written notice complying with the applicable rules established by
the Committee stating that the Option, or a portion thereof, is exercised. The
notice shall be signed by the Optionee or other person then entitled to exercise
the Option or such portion;

         (b) Full payment (in cash or by check) for the shares with respect to
which such Option is exercised; provided that the Committee may, in its
discretion, allow payment, in whole or in part, through the surrender of shares
of Common Stock then issuable upon exercise of the Options having a Fair Market
Value on the date of exercise equal to the aggregate exercise price of the
Options or exercised portion thereof;

         (c) A bona fide written representation and agreement, in a form
satisfactory to the Committee, signed by the Optionee or other person then
entitled to exercise such Options, stating that the shares of Common Stock are
being acquired for his or her own account, for investment and without any
present intention of distributing or reselling said shares or any of them except
as

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may be permitted under the Securities Act and then applicable rules and
regulations thereunder, and that the Optionee or other person then entitled to
exercise such Option or portion will indemnify the Company against and hold it
free and harmless from any loss, damage, expense or liability resulting to the
Company if any sale or distribution of the shares by such person is contrary to
the representation and agreement referred to above. The Committee may, in its
discretion, take whatever additional actions it deems appropriate to insure the
observance and performance of such representation and agreement and to effect
compliance with the Securities Act and any other federal or state securities
laws or regulations. Without limiting the generality of the foregoing, the
Committee may require an opinion of counsel acceptable to it to the effect that
any subsequent transfer of shares acquired on exercise of Options does not
violate the Securities Act, and may issue stop-transfer orders covering such
shares. Share certificates evidencing Common Stock issued on exercise of the
Options shall bear an appropriate legend referring to the provisions of this
subsection (c) and the Stockholders Agreement and the agreements herein. The
written representation and agreement referred to in the first sentence of this
subsection (c) shall, however, not be required if the shares to be issued
pursuant to such exercise have been registered under the Securities Act, and
such registration is then effective in respect of such shares;

         (d) A bona fide written representation and agreement, in a form
satisfactory to the Committee, signed by the Optionee or other person then
entitled to exercise such Option, stating that the Optionee (or other holder of
the Option) shall be deemed to be a signatory to, and to be bound by all of the
terms and provisions of, the Stockholders Agreement, and that such Optionee (or
other holder) agrees that upon request by the Company, he or she will execute a
signature page to such Stockholders Agreement; and

         (e) In the event the Options shall be exercised pursuant to Section 2.1
by any person or persons other than the Optionee, appropriate proof of the right
of such person or persons to exercise the Options.

2.4 CONDITIONS TO ISSUANCE OF STOCK CERTIFICATES. The shares of Common Stock
deliverable upon the exercise of Options may be either previously authorized but
unissued shares or issued shares which have then been reacquired by the Company.
Such shares shall be fully paid and nonassessable. The Company shall not be
required to issue or deliver any certificate or certificates for shares of
Common Stock purchased upon the exercise of Options prior to fulfillment of all
of the following conditions: (a) The admission of such shares to listing on all
stock exchanges on which such class of stock is then listed; and, (b) The
completion of any registration or other qualification of such shares under any
state or federal law or under rulings or regulations of the Securities and
Exchange Commission or of any other governmental regulatory body, which the
Committee shall, in its discretion, deem necessary or advisable; and, (c) The
obtaining of any approval or other clearance from any state or federal
governmental agency which the Committee shall, in its discretion, determine to
be necessary or advisable; and, (d) The payment to the Company (or other
employer corporation) of all amounts which, under federal, state or local tax
law, it is required to withhold upon exercise of the Options in accordance with
Section 3.4; and, (e) The lapse of such reasonable period of time following the
exercise of the Option as the Committee may from time to time establish for
reasons of administrative convenience.

2.5 RIGHTS AS STOCKHOLDER. The holder of the Options shall not be, nor have any
of the rights or privileges of, a stockholder of the Company in respect of any
shares purchasable upon the exercise of any Option unless and until certificates
representing such shares shall have been issued by the Company to such holder.

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                          ARTICLE III: OTHER PROVISIONS

3.1 OPTIONS NOT TRANSFERABLE. Options may not be sold, pledged, assigned, or
transferred in any manner other than by will or the laws of descent and
distribution or pursuant to a QDRO, unless and until the Options have been
exercised, or the shares underlying the Options have been issued, and all
restrictions applicable to such shares have lapsed. No Options or interest or
right therein shall be liable for the debts, contracts or engagements of the
Optionee or his or her successors in interest or shall be subject to disposition
by transfer, alienation, anticipation, pledge, encumbrance, assignment or any
other means whether such disposition be voluntary or involuntary or by operation
of law by judgment, levy, attachment, garnishment or any other legal or
equitable proceedings (including bankruptcy), and any attempted disposition
thereof shall be null and void and of no effect, except to the extent that such
disposition is permitted by the preceding sentence.

3.2 SHARES TO BE RESERVED. The Company shall at all times during the term of the
Options reserve and keep available such number of shares of Common Stock as will
be sufficient to satisfy the requirements of this Agreement.

3.3 CHANGES IN COMMON STOCK OR ASSETS OF THE COMPANY, ACQUISITION OR LIQUIDATION
OF THE COMPANY AND OTHER CORPORATE EVENTS

         (a) In the event that the Committee determines that any dividend or
other distribution (whether in the form of cash, Common Stock, other securities,
or other property), recapitalization, reclassification, stock split, reverse
stock split, reorganization, merger, consolidation, split, spin-off,
combination, repurchase, liquidation, dissolution, or sale, transfer, exchange
or other disposition of all or substantially all of the assets of the Company,
or exchange of Common Stock or other securities of the Company, issuance of
warrants or other rights to purchase Common Stock or other securities of the
Company, or other similar corporate transaction or event, in the Committee's
sole discretion, affects the Common Stock such that an adjustment is determined
by the Committee to be appropriate in order to prevent dilution or enlargement
of the benefits or potential benefits intended to be made available with respect
to the Options, then the Committee shall, in such manner as it may deem
equitable, adjust any or all of: (i) the number and kind of shares of Common
Stock (or other securities or property) subject to the Options, and, (ii) the
exercise price with respect to the Options.

         (b) In the event of any transaction or event described in Section
3.3(a) or any unusual or nonrecurring transactions or events affecting the
Company, any affiliate of the Company, or the financial statements of the
Company or any affiliate, or of changes in applicable laws, regulations, or
accounting principles, the Committee, in its discretion, is hereby authorized to
take any one or more of the following actions whenever the Committee determines
that such action is appropriate in order to prevent dilution or enlargement of
the benefits or potential benefits intended to be made available with respect to
the Options, to facilitate such transactions or events or to give effect to such
changes in laws, regulations or principles: (i) In its sole discretion, and on
such terms and conditions as it deems appropriate, the Committee may provide, by
action taken prior to the occurrence of such transaction or event and either
automatically or upon the Optionee's request, for either the purchase of the
Options (to the extent unexercised) for an amount of cash equal to the amount
that could have been attained upon the exercise of the Options or realization of
the Optionee's rights had such Options been currently exercisable or the
replacement of the Options with other rights or property selected by the
Committee in its sole discretion; (ii) In its sole discretion, the Committee may
provide, by action taken prior to the occurrence of such transaction or event,
that the Option cannot be

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exercised after such event; (iii) In its sole discretion, and on such terms and
conditions as it deems appropriate, the Committee may provide, by action taken
prior to the occurrence of such transaction or event, that for a specified
period of time prior to such transaction or event, the Options shall be
exercisable as to all shares covered thereby, notwithstanding anything to the
contrary in this Agreement; (iv) In its sole discretion, and on such terms and
conditions as it deems appropriate, the Committee may provide, by action taken
prior to the occurrence of such transaction or event, that upon such event, the
Options be assumed by the successor or survivor corporation, or a parent or
subsidiary thereof, or shall be substituted for by similar options, rights or
awards covering the stock of the successor or survivor corporation, or a parent
or subsidiary thereof, with appropriate adjustments as to the number and kind of
shares and prices; and (v) In its sole discretion, and on such terms and
conditions as it deems appropriate, the Committee may make adjustments in the
number and type of shares of Common Stock (or other securities or property)
subject to the Options (to the extent unexercised) and/or in the terms and
conditions of the Options (including the exercise price).

         (c) No adjustment or action described in this Section 4.3 or in any
other provision of this Agreement shall be authorized to the extent that such
adjustment or action would result in short-swing profits liability under Section
16 of the Exchange Act or violate the exemptive conditions of Rule 16b-3 unless
the Committee determines that the Option is not to comply with such exemptive
conditions.

         (d) The number of shares of Common Stock subject to any Option shall
always be rounded to the next whole number.

3.4 TAX WITHHOLDING. The Company shall be entitled to require payment in cash or
deduction from other compensation payable to each Optionee of any sums required
by federal, state or local tax law to be withheld with respect to the issuance,
commencement of exercisability or exercise of the Options. The Committee may, in
its discretion, allow the Optionee to elect to have the Company withhold shares
of Common Stock otherwise issuable under the Options having a Fair Market Value
equal to the sums required to be withheld.

3.5 LIMITATIONS APPLICABLE TO SECTION 16 PERSONS. Notwithstanding any other
provision of this Agreement, the Plan and the Options shall be subject to any
additional limitations set forth in any applicable exemptive rule under Section
16 of the Exchange Act (including any amendment to Rule 16b-3) that are
requirements for the application of such exemptive rule, to the extent the
Optionee is subject to Section 16 of the Exchange Act. To the extent permitted
by applicable law, this Agreement and the Options shall be deemed amended to the
extent necessary to conform to such applicable exemptive rule.

3.6 NOTICES. Any notice to be given under the terms of this Agreement to the
Company shall be addressed to the Company in care of its Secretary, and any
notice to be given to the Optionee shall be addressed to him at the address
given beneath his signature on the Grant Notice. By a notice given pursuant to
this Section 3.6, either party may hereafter designate a different address for
notices to be given to him or it. Any notice which is required to be given to
the Optionee shall, if the Optionee is then deceased, be given to the Optionee's
personal representative if such representative has previously informed the
Company of his or her status and address by written notice under this Section
3.6. Any notice shall be deemed duly given when enclosed in a properly sealed
envelope or wrapper addressed as aforesaid, deposited (with postage prepaid) in
a post office or branch post office regularly maintained by the United States
Postal Service.

3.7 TITLES. Titles are provided herein for convenience only and are not to serve
as a basis for interpretation or construction of this Agreement.

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3.8 CONFORMITY TO LAWS. The Optionee acknowledges that the Plan, this Agreement,
the Options and shares of Common Stock issuable upon exercise of the Options are
subject to compliance with all applicable federal and state laws, rules and
regulations (including, but not limited to, federal and state securities laws)
and to such approvals by any listing, regulatory or governmental authority as
may, in the opinion of counsel for the Company, be necessary or advisable in
connection therewith. To the extent permitted by applicable law, this Agreement
and the Options shall be deemed amended to the extent necessary to conform to
such laws, rules and regulations.

3.9 INVALID PROVISION. The invalidity or unenforceability of any particular
provision hereof shall not affect the other provisions hereof, and this
Agreement shall be construed in all respects as if such invalid or unenforceable
provision was omitted.

3.10 COUNTERPARTS. This Agreement may be executed simultaneously in two or more
counterparts, each of which shall be deemed an original, but all of which
together shall constitute one and the same instrument.

3.11 ASSIGNMENT. Except as otherwise provided herein, no party may assign this
Agreement or any of his or its rights, interests or obligations hereunder
without the prior written consent of the other parties, provided that the
Company's rights and obligations hereunder may be assigned to any Parent
Corporation or Subsidiary or to any successor pursuant to a merger,
consolidation or similar event. Subject to the foregoing, this Agreement and the
respective rights and obligations of the parties hereto shall inure to the
benefit of and be binding upon, the successors and assigns of the parties.

3.12 EFFECT OF OPTIONS UPON OTHER COMPENSATION PLANS. The Options and any
payments with respect thereto shall not constitute "compensation" for purposes
of any pension, welfare or other benefit plan or policy of the Company unless
provided for therein.

3.13 LAW GOVERNING. The laws of the State of New York shall govern the
interpretation, validity and performance of the terms hereof, regardless of the
law that might be applied under principles of conflicts of law.

3.14 VENUE. Any suit hereunder shall be brought in the federal or state courts
in the districts which include Monmouth County, New Jersey and Optionee hereby
agrees and submits to the personal jurisdiction and venue thereof.

                                 Page 11 of 11<PAGE>
                                                                   Exhibit 10.13

                          REGISTRATION RIGHTS AGREEMENT

         This REGISTRATION RIGHTS AGREEMENT, dated as of September [ ], 2006
(this "Agreement"), is 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' Fund, L.P., Sprout IX Plan Investors, L.P., Sprout CEO
Fund L.P. (each of the foregoing, collectively, the "DLJ Entities"), N. Robert
Hammer and Lou Miceli (each of the foregoing, including the DLJ Entities, an
"Investor" and collectively, the "Investors") and CommVault Systems, Inc., a
Delaware corporation (the "Company").

         WHEREAS, the parties hereto previously entered into a Stockholders'
Agreement, dated as of May 22, 1996, as amended by the First Amendment thereto,
dated July 23, 1998, the Second Amendment thereto, dated November 6, 2000, the
Third Amendment thereto, dated February 14, 2002, the Fourth Amendment thereto,
dated September 2, 2003, and the Fifth Amendment thereto, dated May 22, 2006 (as
so amended, the "Original Agreement");

         WHEREAS, the parties hereto desire to amend and restate the Original
Agreement as set forth herein; and

         WHEREAS, in compliance with Section 6.4(a) of the Original Agreement,
this Agreement has been approved by the Board of Directors of the Company and
the signatories hereto represent holders of at least 85% of the Fully Diluted
Common Stock (as defined below) held by parties to the Original Agreement.

         NOW, THEREFORE, in consideration of the foregoing and the covenants of
the parties set forth herein and for other good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, subject to the terms
and conditions set forth herein, the parties hereby agree as follows:

         Section 1. Certain Definitions. In this Agreement the following terms
shall have the following respective meanings:

                  "Commission" shall mean the Securities and Exchange Commission
or any other federal agency at the time administering the Securities Act.

                  "Common Stock" shall mean shares of Common Stock, par value
$0.01 per share, of the Company.

                  "Demand Registration" shall have the meaning ascribed to it in
Section 2(a) of this Agreement.

                  "Exchange Act" shall mean the Securities Exchange Act of 1934,
as amended, and the rules and regulations of the Commission thereunder, all as
the same shall be in effect at the relevant time.
<PAGE>

                  "Fully Diluted" shall mean, with respect to the Common Stock
and without duplication, all outstanding shares and all shares issuable in
respect of stock convertible into or exchangeable for Common Stock, stock
appreciation rights or options, warrants and other irrevocable rights to
purchase or subscribe for Common Stock or stock convertible into or exchangeable
for Common Stock and any Person shall be deemed to own such number of Fully
Diluted shares of Common Stock as such Person beneficially owns or has the right
to acquire from any other Person (including the Company).

                  "Holders" shall mean the Investors, (ii) each Person holding
Registrable Stock as a result of a transfer or assignment to that Person of
Registrable Stock other than pursuant to an effective registration statement or
Rule 144 under the Securities Act and (iii) Persons holding Registrable Stock as
of the date hereof and any permitted transferees hereunder.

                  "Indemnified Party" shall have the meaning ascribed to it in
Section 7(c) of this Agreement.

                  "Indemnifying Party" shall have the meaning ascribed to it in
Section 7(c) of this Agreement.

                  "Initiating Holders" shall mean any Holder or Holders who in
the aggregate hold not less than 10% of the Fully Diluted Common Stock
outstanding.

                  "Other Investors" shall mean N. Robert Hammer and Lou Miceli,
collectively.

                  "Person" shall mean an individual, corporation, partnership,
estate, trust, association, private foundation, joint stock company or other
entity.

                  "Piggyback Notice" shall have the meaning ascribed to it in
Section 3(a) of this Agreement.

                  "Piggyback Registration" shall have the meaning ascribed to it
in Section 3(a) of this Agreement.

                  "Preferred Stock" shall mean the Company's Series A Preferred
Stock, par value $0.01 per share, Series B Preferred Stock, par value $0.01 per
share, Series C Preferred Stock, par value $0.01 per share, Series D Preferred
Stock, par value $0.01 per share, and Series E Preferred Stock, par value $0.01
per share.

                  The terms "Register," "Registered" and "Registration" refer to
a registration effected by preparing and filing a registration statement in
compliance with the Securities Act providing for the sale by the Holders of
Registrable Stock in accordance with the method or methods of distribution
designated by the Holders, and the declaration or ordering of the effectiveness
of such registration statement by the Commission.

                  "Registrable Stock" shall mean (i) Common Stock received upon
conversion of Preferred Stock and (ii) Common Stock issued to the Investors as a
dividend or other distribution.

                                       2
<PAGE>

                  "Registration Request" shall have the meaning ascribed to it
in Section 2(a) of this Agreement.

                  "Rule 144" shall mean Rule 144 promulgated by the Commission
under the Securities Act.

                  "Securities Act" shall mean the Securities Act of 1933, as
amended, and the rules and regulations of the Commission thereunder, all as the
same shall be in effect at the relevant time.

                  "Series AA Holders" shall mean each holder of piggy-back
rights granted under the Amended and Restated Registration Rights Agreement,
dated as of September 2, 2003, relating to shares of the Company's Series AA
Preferred Stock.

                  "Series CC Holders" shall mean each holder of piggy-back
rights granted under the Amended and Restated Registration Rights Agreement,
dated as of September 2, 2003, relating to shares of the Company's Series CC
Preferred Stock.

                   "Suspension Right" shall have the meaning ascribed to it in
Section 2(a) of this Agreement.

                  "S-3 Suspension Right" shall have the meaning ascribed to it
in Section 4(a) of this Agreement.

         Section 2.        Demand Registration.

                  (a) Upon receipt of a written request (a "Registration
Request") from Initiating Holders with respect to Registrable Stock representing
at least 25% of such Initiating Holders' Registrable Stock (or any lesser
percentage having a reasonably anticipated aggregate offering price to the
public of $2,000,000)(a "Demand Registration"), the Company shall (i) promptly
give notice of the Registration Request to all non-requesting Holders and (ii)
prepare and file with the Commission promptly, but in any event within (x) 90
days after its receipt of such Registration Request if the Company had not
conducted an underwritten public offering of the Common Stock before such time
and (y) 45 days after its receipt of such Registration Request if the Company
had conducted an underwritten public offering of the Common Stock before such
time, a registration statement for the purpose of effecting a Registration of
the sale of all Registrable Stock requested to be Registered by the requesting
Holders and any other Holder who requests to have his Registrable Stock included
in such registration statement within ten days after receipt of notice by such
Holder of the Registration Request. The Company shall use commercially
reasonable efforts to effect such Registration as soon as practicable
(including, without limitation, the execution of an undertaking to file
post-effective amendments and appropriate qualification under applicable state
securities laws); and shall keep such Registration continuously effective until
the earlier of (i) the second anniversary of the date that shares of Registrable
Stock are first sold pursuant to such Registration, (ii) the date on which all
shares of Registrable Stock have been sold pursuant to such registration
statement or Rule 144 and (iii) the date on which, in the reasonable opinion of
counsel to the Company, all of the Registrable Stock may be sold in accordance
with Rule 144(k); provided, however, that the Company shall not be obligated to
take any action to effect any such Registration, qualification or compliance
pursuant

                                       3
<PAGE>

to this Section 2 (i) in any particular jurisdiction in which the Company would
become subject to taxation or would be required to execute a general consent to
service of process in effecting such Registration, qualification or compliance
unless the Company is already subject to taxation or service in such
jurisdiction or (ii) during the period starting with the date 60 days prior to
the Company's good faith estimate of the date of filing of, and ending on a date
180 days after the effective date of, a Company-initiated registration.

         Notwithstanding the foregoing, the Company shall have the right (the
"Suspension Right") to defer such filing (or suspend sales under any filed
registration statement or defer the updating of any filed registration statement
and suspend sales thereunder) at any time or from time to time, for a period of
not more than 90 days during any period of 365 days, if the Company shall
furnish to the Holders a certificate signed by an executive officer or any
trustee of the Company stating that, in the good faith judgment of the Company,
it would be detrimental to the Company and its shareholders to file such
registration statement or amendment thereto at such time (or continue sales
under a filed registration statement) and therefore the Company has elected to
defer the filing of such registration statement (or suspend sales under a filed
registration statement).

         (b) If a Demand Registration is an underwritten Demand Registration
with other holders requesting to include their securities pursuant to other
piggy back rights and the managing underwriters advise the Company in writing
that, in their opinion, the number of securities to be included in such
registration exceeds the number that can be sold in an orderly manner in such
offering within a price range acceptable to the Holders, the Company will
include securities in such registration in the following order of priority:

                (i)     first, the Registrable Stock requested to be included in
         such registration by the Holders exercising rights pursuant to Section
         2(a) and any securities requested to be included therein by the Series
         AA Holders or the Series CC Holders, pro rata among all such holders
         based upon the number of shares of such securities requested for
         inclusion in such registration by each such holder;

                (ii)     second, any securities requested to be included therein
         by any other holders pursuant to such holders' piggyback rights, if
         any, pro rata based upon the 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 Company, if any.

         (c)      The Company shall not be required to effect more than two
Registrations pursuant to this Section 2.

         Section 3.      Piggyback Registrations.

                  (a)    As long as the Holders hold any Registrable Stock, if
the Company proposes to register any of its common equity securities or any
securities convertible into its common equity securities under the Securities
Act (other than pursuant to (i) a registration on Form S-4 or any successor
form, or (ii) an offering of securities in connection with an employee

                                       4

<PAGE>

benefit, share dividend, share ownership or dividend reinvestment plan) and the
registration form to be used may be used for the registration of Registrable
Stock, the Company shall give prompt written notice to all Holders of its
intention to effect such a registration (each a "Piggyback Notice") and, subject
to subparagraph 3(c) below, the Company shall include in such registration all
Registrable Stock with respect to which the Company has received written
requests for inclusion therein within ten days after the date of receipt of the
Piggyback Notice (a "Piggyback Registration"), unless, in the case of an
underwritten Piggyback Registration, the managing underwriters advise the
Company in writing that in their opinion, the inclusion of Registrable Stock
would adversely interfere with such offering. Nothing herein shall affect the
right of the Company to withdraw any such registration in its sole discretion.

         (b)      If a Piggyback Registration is a primary underwritten
registration and the managing underwriters advise the Company in writing that,
in their opinion, the number of securities requested to be included in such
registration exceeds the number which can be sold in an orderly manner within a
price range acceptable to the Company, the Company will include securities in
such registration in the following order of priority:

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

                 (ii)     second, the securities requested to be included in
         such registration by the Series AA Holders and the Series CC Holders,
         if any, pro rata among all such holders based on the number of
         shares of such securities requested for inclusion in such registration
         by each such holder; and

                (iii)    third, the Registrable Stock requested to 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 based upon 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 Piggyback Registration is a secondary registration
on behalf of holders of the Company's securities other than the Holders of
Registrable Stock and, if the Piggyback Registration is an underwritten
Piggyback Registration and the managing underwriters advise the Company in
writing that, in their opinion, the number of securities requested to be
included in such registration exceeds the number which can be sold in an orderly
manner in such offering within a price range acceptable to the holders initially
requesting such registration, the Company will include securities in such
registration in the following order of priority:

                  (i)      first, the securities requested to be included in
         such registration by the holders requesting such registration and the
         securities of the Series AA Holders and the Series CC Holders requested
         to be included therein, if any, pro rata among all such holders based
         on the number of shares of such securities requested for inclusion in
         such registration by each such holder;

                  (ii)     second, the Registrable Stock requested to 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 among all

                                       5
<PAGE>
         such holders based on the 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 Company, if any.

                  (d)      In the case of an underwritten Piggyback
Registration, the Company will have the right to select the investment banker(s)
and manager(s) to administer the offering. If requested by the underwriters for
any underwritten offerings by Holders, under a registration requested pursuant
to Section 2(a), the Company will enter into a customary underwriting agreement
with such underwriters for such offering, to contain such representations and
warranties by the Company and such other terms which are customarily contained
in agreements of this type (including indemnification provisions). The Holders
shall be a party to such underwriting agreement and may, at their option,
require that any or all of the conditions precedent to the obligations of such
underwriters under such underwriting agreement be conditions precedent to the
obligations of Holders. The Holders shall not be required to make any
representations or warranties to or agreement with the Company or the
underwriters other than representations, warranties or agreements regarding the
Holders and the Holders' intended method of distribution and any other
representations or warranties required by law.

         Section 4.        S-3 Registration

         (a)    The Company shall use its commercially reasonable efforts to
qualify for registration on Form S-3 or any comparable or successor form or
forms. After the Company has qualified for use of Form S-3, in addition to the
rights contained in Sections 2 and 3, the Holders of Registrable Securities
shall have the right to request registrations on Form S-3 (such requests shall
be in writing and shall state the number of shares of Registrable Securities to
be disposed of and the intended methods of disposition of such shares by such
Holder or Holders). The Company shall use commercially reasonable efforts to
effect such Registration as soon as practicable (including, without limitation,
the execution of an undertaking to file post-effective amendments and
appropriate qualification under applicable state securities laws); and shall
keep such Registration continuously effective until the earlier of (i) the date
on which all shares of Registrable Stock have been sold pursuant to such
registration statement or Rule 144 and (ii) the date on which, in the reasonable
opinion of counsel to the Company, all of the Registrable Stock may be sold in
accordance with Rule 144(k), provided, however, that the Company shall not be
obligated to effect any such registration (i) if the Holders, together with the
holders of any other securities of the Company entitled to inclusion in such
registration, propose to sell Registrable Securities and such other securities
(if any) on Form S-3 at an aggregate price to the public of less than
$1,000,000, (ii) in the circumstances described in the proviso to the first
paragraph of Section 2(a), (iii) if the Company shall furnish the certification
described in the second paragraph of Section 2(a) (but subject to the
limitations set forth therein) or (iv) if, in a given twelve-month period, the
Company has effected one such registration in such period.

                Notwithstanding the foregoing, the Company shall have the
right (the "S-3 Suspension Right") (i) to defer such filing for up to 60 days or
suspend sales under any filed registration statement or (ii) defer the updating
of any filed registration statement and suspend sales thereunder at any time or
from time to time, for a period of not more than 90 days during

                                       6
<PAGE>

any period of 365 days, if the Company shall furnish to the Holders a
certificate signed by an executive officer or any trustee of the Company stating
that, in the good faith judgment of the Company, it would be detrimental to the
Company and its shareholders to file such registration statement or amendment
thereto at such time (or continue sales under a filed registration statement)
and therefore the Company has elected to defer the filing of such registration
statement (or suspend sales under a filed registration statement).

         (b) The Holders' rights under this Section 4 shall terminate upon the
earlier to occur of (i) the fifth anniversary of the fifth anniversary of the
date of the closing of the underwritten initial public offering of the Common
Stock and (ii) the date on which, in the reasonable opinion of counsel to the
Company, all of the Registrable Stock may be sold in accordance with Rule
144(k).

         Section 5.       Registration Procedures.

                 (a)      The Company shall promptly notify the Holders of the
occurrence of the following events:

                          (i)      when any registration statement relating to
         the Registrable Stock or post-effective amendment thereto filed with
         the Commission has become effective;

                          (ii)     the issuance by the Commission of any stop
         order suspending the effectiveness of any registration statement
         relating to the Registrable Stock;

                          (iii)    the suspension of an effective registration
         statement by the Company in accordance with the last paragraph of
         Section 2(a) or Section 4(a) hereof;

                          (iv)     the Company's receipt of any notification of
         the suspension of the qualification of any Registrable Stock covered by
         a registration statement for sale in any jurisdiction; and

                          (v) the existence of any event, fact or circumstance
         that results in a registration statement or prospectus relating to
         Registrable Stock or any document incorporated therein by reference
         containing an untrue statement of material fact or omitting to state a
         material fact required to be stated therein or necessary to make the
         statements therein not misleading during the distribution of
         securities.

         The Company agrees to use commercially reasonable efforts to obtain the
withdrawal of any order suspending the effectiveness of any such registration
statement or any state qualification as promptly as possible. The Holders agree
that upon receipt of any notice from the Company of the occurrence of any event
of the type described in Sections 5(a)(ii), (iii), (iv) or (v) to immediately
discontinue their disposition of Registrable Stock pursuant to any registration
statement relating to such securities until the Holders receive written notice
from the Company that such disposition may be made.

                  (b)      The Company shall provide to the Holders, at no cost
to the Holders, a copy of the registration statement and any amendment thereto
used to effect the Registration of the Registrable Stock, each prospectus
contained in such registration statement or post-effective

                                       7
<PAGE>

amendment and any amendment or supplement thereto and such other documents as
the requesting Holders may reasonably request in order to facilitate the
disposition of the Registrable Stock covered by such registration statement. The
Company consents to the use of each such prospectus and any supplement thereto
by the Holders in connection with the offering and sale of the Registrable Stock
covered by such registration statement or any amendment thereto. If the Common
Stock is listed on a national securities exchange at any time during the period
in which the Company is obligated to keep the registration statement effective
pursuant to Section 2(a), the Company shall also file a sufficient number of
copies of the prospectus and any post-effective amendment or supplement thereto
with such exchange so as to enable the Holders to have the benefits of the
prospectus delivery provisions of Rule 153 under the Securities Act.

                  (c)      The Company shall use commercially reasonable efforts
to cause the Registrable Stock covered by a registration statement to be
registered with or approved by such state securities authorities as may be
necessary to enable the Holders to consummate the disposition of such stock
pursuant to the plan of distribution set forth in the registration statement;
provided, however, that the Company shall not be obligated to take any action to
effect any such Registration, qualification or compliance pursuant to this
Section 5 in any particular jurisdiction in which the Company would become
subject to taxation or would be required to execute a general consent to service
of process in effecting such Registration, qualification or compliance unless
the Company is already subject to taxation or service in such jurisdiction.

                  (d)      Subject to the Company's Suspension Right or an S-3
Suspension Right, if any event, fact or circumstance requiring an amendment to a
registration statement relating to the Registrable Stock or supplement to a
prospectus relating to the Registrable Stock shall exist, immediately upon
becoming aware thereof the Company shall notify the Holders and prepare and
furnish to the Holders a post-effective amendment to the registration statement
or supplement to the prospectus or any document incorporated therein by
reference or file any other required document so that, as thereafter delivered
to the purchasers of the Registrable Stock, the prospectus will not contain an
untrue statement of a material fact or omit to state any material fact required
to be stated therein or necessary to make the statements therein not misleading.

                  (e)      The Company shall use commercially reasonable efforts
(including the payment of any listing or quotation fees) to obtain the listing
or quotation of all Registrable Stock covered by the registration statement on
each securities exchange or inter-dealer automated quotation system on which
securities of the same class or series are then listed.

                  (f)      The Company and the Holders shall use commercially
reasonable efforts to comply with the Securities Act and the Exchange Act in
connection with the offer and sale of Registrable Stock pursuant to a
registration statement, and, as soon as reasonably practicable following the end
of any fiscal year during which a registration statement effecting a
Registration of the Registrable Stock shall have been effective, to make
available to the Holders an earnings statement satisfying the provisions of
Section 11(a) of the Securities Act.

                  (g)      The Company shall cooperate with the selling Holders
to facilitate the timely preparation and delivery of certificates representing
Registrable Stock to be sold pursuant to a Registration and not bearing any
Securities Act legend; and enable certificates for such

                                       8
<PAGE>

Registrable Stock to be issued for such numbers of stock and registered in such
names as the Holders may reasonably request at least two business days prior to
any sale of Registrable Stock.

         Section 6.     Expenses of Registration. All reasonable expenses, other
than underwriting discounts and commissions and transfer taxes, incurred in
connection with registrations, filings or qualifications pursuant to Sections 2,
3, 4 and 5 hereof, including, without limitation, all registration, listing and
qualifications fees, printers and accounting fees, the fees and disbursements of
counsel for the Company and the reasonable fees and disbursements of one counsel
selected by the Holders shall be borne 50% by the Holders participating in the
particular registration and 50% by the Company.

         Section 7.     Indemnification.

                 (a)    The Company shall indemnify each Holder, each Holder's
officers and directors, and each person controlling such Holder within the
meaning of Section 15 of the Securities Act, against all expenses, claims,
losses, damages and liabilities (including reasonable legal fees and expenses),
arising out of or based on any untrue statement (or alleged untrue statement) of
a material fact contained in any registration statement or prospectus relating
to the Registrable Stock, or any amendment or supplement thereto, or based on
any omission (or alleged omission) to state therein a material fact required to
be stated therein or necessary to make the statements therein not misleading,
provided, however, that the Company shall not be liable in any such case to the
extent that any such claim, loss, damage, liability or expense arises out of or
is based on any untrue statement or omission or alleged untrue statement or
omission, made in reliance upon and in conformity with information furnished in
writing to the Company by such Holder or underwriter for inclusion therein.

                 (b)    Each Holder, if Registrable Stock held by such Holder is
included in the securities as to which such registration is being effected,
shall indemnify the Company, each of its trustees and each of its officers who
signs the registration statement, each underwriter, if any, of the Company's
securities covered by such registration statement, and each person who controls
the Company or such underwriter within the meaning of Section 15 of the
Securities Act, against all claims, losses, damages and liabilities (including
reasonable legal fees and expenses) arising out of or based on any untrue
statement (or alleged untrue statement) of a material fact contained in any such
registration statement or prospectus, or any amendment or supplement thereto, or
based on any omission (or alleged omission) to state therein a material fact
required to be stated therein or necessary to make the statements therein not
misleading, in each case to the extent, but only to the extent, that such untrue
statement (or alleged untrue statement) or omission (or alleged omission) is
made in such registration statement or prospectus, in reliance upon and in
conformity with information furnished in writing to the Company by such Holder
for inclusion therein.

                 (c)    Each party entitled to indemnification under this
Section 7 (the "Indemnified Party") shall give notice to the party required to
provide indemnification (the "Indemnifying Party") promptly after such
Indemnified Party has actual knowledge of any claim as to which indemnity may be
sought, but the omission to so notify the Indemnifying Party shall not relieve
it from any liability which it may have to the Indemnified Party pursuant to the
provisions of this Section 7 except to the extent of the actual damages suffered
by such delay in

                                       9
<PAGE>

notification. The Indemnifying Party shall assume the defense of such action,
including the employment of counsel to be chosen by the Indemnifying Party to be
reasonably satisfactory to the Indemnified Party, and payment of expenses. The
Indemnified Party shall have the right to employ its own counsel in any such
case, but the legal fees and expenses of such counsel shall be at the expense of
the Indemnified Party, unless the employment of such counsel shall have been
authorized in writing by the Indemnifying Party in connection with the defense
of such action, or the Indemnifying Party shall not have employed counsel to
take charge of the defense of such action or the Indemnified Party shall have
reasonably concluded that there may be defenses available to it or them which
are different from or additional to those available to the Indemnifying Party
(in which case the Indemnifying Party shall not have the right to direct the
defense of such action on behalf of the Indemnified Party), in any of which
events such fees and expenses shall be borne by the Indemnifying Party. No
Indemnifying Party, in the defense of any such claim or litigation, shall,
except with the consent of each Indemnified Party, consent to entry of any
judgment or enter into any settlement which does not include as an unconditional
term thereof the giving by the claimant or plaintiff to such Indemnified Party
of a release from all liability in respect to such claim or litigation.

                  (d)      If the indemnification provided for in this Section 7
is unavailable to a party that would have been an Indemnified Party under this
Section 7 in respect of any expenses, claims, losses, damages and liabilities
referred to herein, then each party that would have been an Indemnifying Party
hereunder shall, in lieu of indemnifying such Indemnified Party, contribute to
the amount paid or payable by such Indemnified Party as a result of such
expenses, claims, losses, damages and liabilities in such proportion as is
appropriate to reflect the relative fault of the Indemnifying Party on the one
hand and such Indemnified Party on the other in connection with the statement or
omission which resulted in such expenses, claims, losses, damages and
liabilities, as well as any other relevant equitable considerations. The
relative fault shall be determined by reference to, among other things, whether
the untrue or alleged untrue statement of a material fact or the omission or
alleged omission to state a material fact relates to information supplied by the
Indemnifying Party or such Indemnified Party and the parties' relative intent,
knowledge, access to information and opportunity to correct or prevent such
statement or omission. The Company and each Holder agree that it would not be
just and equitable if contribution pursuant to this Section were determined by
pro rata allocation or by any other method of allocation which does not take
account of the equitable considerations referred to above in this Section 7(d).

                  (e)      No person guilty of fraudulent misrepresentation
(within the meaning of Section 11(f) of the Securities Act) shall be entitled to
contribution from any person who was not guilty of such fraudulent
misrepresentation.

                  (f)      In no event shall any Holder be liable for any
expenses, claims, losses, damages or liabilities pursuant to this Section 7 in
excess of the net proceeds to such Holder of any Registrable Stock sold by such
Holder pursuant to the registration statement in question.

         Section 8.     Information to be Furnished by Holders. Each Holder
shall furnish to the Company such information as the Company may reasonably
request and as shall be required in connection with the Registration and related
proceedings referred to in Section 2 or Section 3 hereof. If any Holder fails to
provide the Company with such information within 10 days of

                                       10
<PAGE>

receipt of the Company's request, the Company's obligations under Section 2 or
Section 3 hereof, as applicable, with respect to such Holder or the Registrable
Stock owned by such Holder shall be suspended until such Holder provides such
information.

         Section 9.        Rule 144 Sales.

                  (a)      The Company shall use its commercially reasonable
efforts to file the reports required to be filed by the Company under the
Exchange Act, so as to enable any Holder to sell Registrable Stock pursuant to
Rule 144 under the Securities Act.

                  (b)      In connection with any sale, transfer or other
disposition by any Holder of any Registrable Stock pursuant to Rule 144 under
the Securities Act, the Company shall cooperate with such Holder to facilitate
the timely preparation and delivery of certificates representing Registrable
Stock to be sold and not bearing any Securities Act legend, and enable
certificates for such Registrable Stock to be for such number of shares and
registered in such names as the selling Holder may reasonably request at least
two business days prior to any sale of Registrable Stock.

         Section 10.    Assignment of Registration Rights. The rights of the
Holders hereunder, including the right to have the Company register Registrable
Stock pursuant to this Agreement, shall be automatically assignable by each
Holder to any transferee of all or any portion of the shares of Preferred Stock
or the Registrable Stock if: (i) the Holder agrees in writing with the
transferee or assignee to assign such rights, and a copy of such agreement is
furnished to the Company after such assignment, (ii) the Company is furnished
with written notice of (a) the name and address of such transferee or assignee,
and (b) the securities with respect to which such registration rights are being
transferred or assigned, (iii) following such transfer or assignment, the
further disposition of such securities by the transferee or assignee is
restricted under the Securities Act and applicable state securities laws, (iv)
the transferee or assignee agrees in writing for the benefit of the Company to
be bound by all of the provisions contained herein, and (v) such transfer of the
Registered Stock shall have been made in accordance with the applicable
requirements of Section 5(f) of the Purchase Agreement.

         Section 11.       Miscellaneous.

                  (a)      Governing Law; Submission to Jurisdiction. This
Agreement shall be governed by, and construed and enforced in accordance with,
the laws of the State of Delaware.

                  (b)      WAIVER OF JURY TRIAL. THE COMPANY AND THE INVESTORS
HEREBY WAIVE ANY RIGHT THEY MAY HAVE TO A TRIAL BY JURY IN RESPECT OF ANY
ACTION, PROCEEDING OR LITIGATION DIRECTLY OR INDIRECTLY ARISING OUT OF, UNDER OR
IN CONNECTION WITH THIS AGREEMENT OR THE TRANSACTIONS CONTEMPLATED THEREBY.

                  (c)      Entire Agreement. This Agreement constitutes the
entire agreement, and supersedes all other prior agreements and understandings,
both written and oral, among the parties hereto and their affiliates with
respect to the matters set forth herein.

                                       11
<PAGE>

                  (d)      Amendments and Waivers. No provision of this
Agreement may be waived other than by an instrument in writing signed by the
party to be charged with enforcement and no provision of this Agreement may be
amended other than by an instrument in writing signed by the Company and each
Investor.

                  (e)      Notices. Each notice, demand, request, request for
approval, consent, approval, disapproval, designation or other communication
(each of the foregoing being referred to herein as a notice) required or desired
to be given or made under this Agreement shall be in writing (except as
otherwise provided in this Agreement), and shall be effective and deemed to have
been received (i) when delivered in person, (ii) when sent by fax with receipt
acknowledged, (iii) five days after having been mailed by certified or
registered United States mail, postage prepaid, return receipt requested, or
(iv) the next business day after having been sent by a nationally recognized
overnight mail or courier service, receipt requested. Notices shall be addressed
as follows: (a) if to an Investor (other than Microsoft), at the Investor's
address or fax number set forth below its signature hereon, or at such other
address or fax number as the Investor shall have furnished to the Company in
writing, or (b) if to any assignee or transferee of an Investor, at such address
or fax number as such assignee or transferee shall have furnished the Company in
writing, (c) if to Microsoft or the Company, at the address set forth below. Any
notice or other communication required to be given hereunder to a Holder in
connection with a registration may instead be given to the designated
representative of such Holder.

                  If to the Company or any Other Investor:

                  CommVault Systems, Inc.
                  2 Crescent Place
                  Oceanport, New Jersey 07757-0900
                  Facsimile: (732) 870-4514
                  Attn: N. Robert Hammer

                  with a copy to:

                  Mayer, Brown, Rowe & Maw LLP
                  71 South Wacker Drive
                  Chicago, IL 60606-4637
                  Facsimile: (312) 701-7711
                  Attn: Philip J. Niehoff

                  if to the DLJ Entities, to:

                  DLJ Merchant Banking Partners, L.P.
                  DLJ International Partners, C.V.
                  DLJ Offshore Partners, C.V.
                  DLJ Merchant Banking Funding, Inc.
                  11 Madison Avenue
                  New York, New York 10010

                                       12
<PAGE>

                  Attention: Dan Pulver
                  Fax: (212) 538-2989

                  and to:

                  DLJ Capital Corporation
                  DLJ First ESC, L.P.
                  DLJ ESC II, L.P.
                  Sprout Entrpreneurs' Fund, L.P.
                  Sprout Growth II, L.P.
                  Sprout Capital VII, L.P.
                  Sprout Capital IX, L.P.
                  Sprout IX Plan Investors, L.P.
                  Sprout CEO Fund L.P.
                  3000 Sand Hill Road
                  Building 3, Suite 170
                  Menlo Park, California 94025
                  Attention: Keith B. Geeslin
                  Fax: (650)234-2779

                  with a copy to:

                  Davis Polk & Wardwell
                  450 Lexington Avenue
                  New York, New York 10017
                  Attention: George R. Bason, Jr.
                  Fax: (212) 450-3340

                  and to:

                  Schulte Roth & Zabel LLP
                  919 Third Avenue
                  New York, New York 10022
                  Attention: Phyllis A. Schwartz
                  Fax: (212) 593-5955

                  (f)      Counterparts. This Agreement may be executed in one
or more counterparts, each of which shall be deemed an original but all of which
shall constitute one and the same instrument.

                  (g)      Severability. If any provision of this Agreement
shall be held invalid, illegal or unenforceable, the validity, legality or
enforceability of the other provisions hereof shall not be affected thereby, and
there shall be deemed substituted for the provision at issue a valid, legal and
enforceable provision as similar as possible to the provision at issue.

                  (h)      Headings. The headings herein are for convenience of
reference only, do not constitute part of this Agreement and shall not be deemed
to limit or otherwise affect any of the provisions hereof.

                                       13
<PAGE>

                  (i)      Successors and Assigns. This Agreement shall be
binding upon and inure to the benefit of the parties and their successors and
assigns. Except as provided herein, neither the Company nor any Investor shall
assign this Agreement or any rights or obligations hereunder.

                  (j)      Equitable Relief. The Company and the Holders
acknowledge that a breach by it of its obligations hereunder will cause
irreparable harm to the other party by vitiating the intent and purpose of the
transactions contemplated hereby. Accordingly, the Company and the Holders
acknowledge that the remedy at law for a breach of its obligations hereunder
will be inadequate and agree, in the event of a breach or threatened breach by
the Company or the Holders of the provisions of this Agreement, that a party
shall be entitled, in addition to all other available remedies, (i) to an
injunction restraining any breach and requiring immediate issuance and transfer,
without the necessity of showing economic loss and without any bond or other
security being required, and (ii) to compel specific performance of another
party under this Agreement in accordance with the terms and conditions of this
Agreement in any court of the United States or any State thereof having
jurisdiction.

                  (k)      Joint Participation in Drafting. Each party to this
Agreement has participated in the negotiation and drafting of this Agreement. As
such, the language used herein shall be deemed to be the language chosen by the
parties hereto to express their mutual intent, and no rule of strict
construction will be applied against any party to this Agreement.

                  (l)      Further Assurances. Each party shall do and perform,
or cause to be done and performed, all such further acts and things, and shall
execute and deliver all such other agreements, certificates, instruments and
documents, as the other party may reasonably request in order to carry out the
intent and accomplish the purposes of this Agreement and the consummation of the
transactions contemplated hereby.

                  (m)      Third Party Beneficiaries. This Agreement is intended
for the benefit of the parties hereto and their respective permitted successors
and assigns, and is not for the benefit of, nor may any provision hereof be
enforced by, any other person.

                            [Signature pages follow.]

                                       14
<PAGE>

         IN WITNESS WHEREOF, the parties hereto have executed this Agreement as
of the date first above written.

                                        COMMVAULT SYSTEMS, INC.

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

                                        DLJ MERCHANT BANKING PARTNERS, L.P.

                                        By: DLJ Merchant Banking, Inc.
                                            Managing General Partner

                                        By:
                                           ------------------------------------
                                           Name:
                                           Attorney-In-Fact

                                        DLJ INTERNATIONAL PARTNERS, C.V.

                                        By: DLJ Merchant Banking, Inc.
                                        Advisory General Partner

                                        By:
                                           ------------------------------------
                                           Name:
                                           Attorney-In-Fact

                                        DLJ OFFSHORE PARTNERS, C.V.

                                        By: DLJ Merchant Banking, Inc.
                                        Advisory General Partner

                                        By:
                                           ------------------------------------
                                            Name:
                                            Attorney-In-Fact

<PAGE>

                                        DLJ MERCHANT BANKING FUNDING, INC.

                                        By:
                                           ------------------------------------
                                            Name:
                                            Attorney-In-Fact

<PAGE>

                                        DLJ CAPITAL CORPORATION

                                        By:
                                           ------------------------------------
                                            Name:
                                            Attorney-In-Fact

                                        DLJ FIRST ESC, L.P.
                                        By:  DLJ LBO Management Corporation,
                                         its General Partner

                                        By:
                                           ------------------------------------
                                            Name:
                                            Attorney-In-Fact

                                        DLJ ESC II, L.P.
                                        By:  DLJ LBO Management Corporation,
                                         its General Partner

                                        By:
                                           ------------------------------------
                                            Name:
                                            Attorney-In-Fact

                                        SPROUT GROWTH II, L.P.

                                        By: DLJ Capital Corporation
                                        Managing General Partner

                                        By:
                                           ------------------------------------
                                            Name:
                                            Attorney-In-Fact
<PAGE>

                                        SPROUT CAPITAL VII, L.P.
                                        By: DLJ Capital Corporation
                                        Managing General Partner

                                        By:
                                           ------------------------------------
                                            Name:
                                            Attorney-In-Fact

                                        SPROUT CAPITAL IX, L.P.
                                        By: DLJ Capital Corporation
                                        Managing General Partner

                                        By:
                                           ------------------------------------
                                            Name:
                                            Attorney-In-Fact

                                        SPROUT IX PLAN INVESTORS, L.P.
                                        By: DLJ Capital Corporation
                                        Managing General Partner

                                        By:
                                           ------------------------------------
                                            Name:
                                            Attorney-In-Fact

                                        SPROUT CEO FUND L.P.
                                        By: DLJ Capital Corporation
                                        Managing General Partner

                                        By:
                                           ------------------------------------
                                            Name:
                                            Attorney-In-Fact

<PAGE>

                                        SPROUT ENTREPRENEURS' FUND
                                        By: DLJ Capital Corporation
                                        Managing General Partner

                                        By:
                                           ------------------------------------
                                            Name:
                                            Attorney-In-Fact

                                        ---------------------------------------
                                        N. ROBERT HAMMER

                                        ---------------------------------------
                                        LOU MICELI

<PAGE>

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