(MAYER, BROWN, ROWE & Maw LLP LOGO)

June 30, 2006 Mayer, Brown, Rowe & Maw LLP
71 South Wacker Drive
Chicago, Illinois 60606-4637

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

By EDGAR & UPS

Securities and Exchange Commission
Division of Corporate Finance
Attention: Mark P. Shuman, Branch Chief - Legal
100 F Street, N.E.
Washington, D.C. 20549

Re: CommVault Systems, Inc. Amendment No. 1 to
Registration Statement on Form S-1 filed
May 3, 2006 (File No.333-132550)

Dear Mr. Shuman:

This letter responds to the Staff's comment letter, dated May 26, 2006,
addressed to N. Robert Hammer, Chairman of the Board, President and Chief
Executive Officer of CommVault Systems, Inc. ("CommVault"), related to the
above-referenced filing. CommVault's responses to the Staff's comments are set
forth herein. To facilitate the Staff's review, CommVault's responses are set
forth below the headings and numbered comments used in the Staff's comment
letter, which are reproduced in bold face text. The supplemental materials
referenced herein will accompany the hard copy of this letter, which has been
forwarded to you via overnight courier. CommVault is contemporaneously filing an
amended Form S-1.

AMENDMENT NO. 1 TO REGISTRATION STATEMENT ON FORM S-1

INSIDE FRONT COVER PAGE

1. WE NOTE YOUR RESPONSE TO COMMENT 4 OF OUR LETTER DATED APRIL 13, 2006;
HOWEVER, YOUR ARTWORK CONTINUES TO CONTAIN EXTENSIVE NARRATIVE TEXT
THAT IS DIFFICULT TO FOLLOW. AS NOTED IN OUR PRIOR COMMENT, PLEASE
LIMIT YOUR GRAPHIC ARTWORK TO A PICTORIAL OR GRAPHIC REPRESENTATION OF
YOUR PRODUCTS OR BUSINESS AND USE TEXT ONLY TO THE EXTENT NECESSARY TO
EXPLAIN BRIEFLY THE VISUALS IN THE PRESENTATION. WE NOTE YOUR RESPONSE
THAT THE CURRENT TEXT IS NECESSARY TO EXPLAIN THE VISUALS PRESENTED IN
THE GRAPHIC. THE TEXT, HOWEVER, CURRENTLY APPEARS TOO EXCESSIVE AND
OVERWHELMS THE VISUAL PRESENTATION. PLEASE REFER TO SECTION VIII OF
OUR MARCH 31, 2001 UPDATE TO OUR CURRENT ISSUES AND RULEMAKING PROJECTS
OUTLINE FOR ADDITIONAL GUIDANCE AND REVISE ACCORDINGLY.

The artwork has been revised as requested.

BerlinBrussels Charlotte Chicago Cologne Frankfurt Houston London Los
Angeles New York Palo Alto Paris Washington, D.C.
Independent Mexico City Correspondent: Jauregui, Navarrete y Nader S.C.

Mayer, Brown, Rowe & Maw LLP operates in combination with our associated
English limited liability partnership in the offices listed above.

Mayer, Brown, Rowe & Maw LLP

Securities and Exchange Commission
June 30, 2006
Page 2

PROSPECTUS SUMMARY, PAGE 1

2. WE NOTE YOUR REVISED DISCLOSURE IN RESPONSE TO COMMENT 6 OF OUR LETTER
DATED APRIL 13, 2006. PLEASE ELABORATE OR QUANTIFY ON YOUR USE OF THE TERM
"SIGNIFICANT DEPLOYMENT."

The prospectus has been revised as requested.

3. IN YOUR RESPONSE TO COMMENT 7 OF OUR LETTER DATED APRIL 13, 2006 YOU
INDICATE THAT THE MARKETING STUDIES YOU EXCERPT ARE NOT AVAILABLE TO
THE PUBLIC WITHOUT COST OR AT NOMINAL COST. AS SUCH, PLEASE PROVIDE
CONSENTS OF THE AUTHORS OF THE REFERENCED REPORTS THAT CONFORM TO RULE
436 UNDER THE SECURITIES ACT AND ITEM 601(b)(23) OF REGULATION S-K.
ALTERNATIVELY, ELIMINATE THE REFERENCE TO THE AUTHORITIES YOU CITE AND
INDICATE THAT THE MARKET DATA YOU SUMMARIZE IN THE PROSPECTUS REPRESENT
THE VIEWS OF COMMVAULT.

The prospectus has been revised as requested.

4. WE NOTE YOUR RESPONSE TO COMMENT 22 OF OUR LETTER DATED APRIL 13, 2006 AND
YOUR DISCLOSURE IN LIQUIDITY AND CAPITAL RESOURCES ON PAGE 47 SUMMARIZING
YOUR PRIVATE PLACEMENTS. PLEASE BRIEFLY SUMMARIZE THESE PRIVATE PLACEMENTS
IN YOUR PROSPECTUS SUMMARY AND RELATE THEM TO THE TRANSACTIONS PLANNED IN
CONNECTION WITH THE OFFERING. PLEASE ALSO BRIEFLY DISCUSS THE INTERESTS OF
CREDIT SUISSE IN THE TRANSACTIONS.

The prospectus has been revised as requested.

5. IT APPEARS THAT THE LETTER AGREEMENT DATED FEBRUARY 8, 2002 YOU MENTION IN
YOUR RESPONSE TO COMMENT 11 OF OUR LETTER DATED APRIL 13, 2006 SHOULD BE
FILED AS AN EXHIBIT TO YOUR REGISTRATION STATEMENT PURSUANT TO ITEM
601(b)(10)(i) OF REGULATION S-K.

The letter agreement has been filed as an exhibit to the Registration Statement.

6. WITH RESPECT TO YOUR RESPONSE TO COMMENT 12 OF OUR LETTER DATED APRIL
13, 2006, PLEASE ADVISE US WHETHER EACH INVESTOR IS AN ACCREDITED
INVESTOR. PLEASE ALSO PROVIDE FOR OUR REVIEW ANY AGREEMENTS RELATED TO
YOUR CONCURRENT PRIVATE PLACEMENT. WE FURTHER NOTE YOUR RESPONSE TO
COMMENT 44 OF OUR LETTER DATED APRIL 13, 2006 AS TO THE PRIVATE
PLACEMENT AGREEMENTS. IT APPEARS THAT THE FILING OF SUCH AGREEMENTS
MAY BE NECESSARY PURSUANT TO ITEMS 601(b)(10)(i) AND (II)(A) OF
REGULATION S-K. PLEASE FILE OR OTHERWISE ADVISE.

The requested documentation is located behind Tab A in the binder of
supplemental material accompanying this filing. The agreements are immaterial in
amount and significance and do not fall within the requirements set forth under
Items 601(b)(10)(i) or (ii)(A) of Regulation S-K.

Mayer, Brown, Rowe & Maw LLP

Securities and Exchange Commission
June 30, 2006
Page 3

7. WE NOTE YOUR RESPONSE TO COMMENT 17 OF OUR LETTER DATED APRIL 13, 2006.
PLEASE BRIEFLY DISCUSS IN YOUR PROSPECTUS SUMMARY THE FACT THAT A
SUBSTANTIAL PORTION OF YOUR REVENUE HAS BEEN DERIVED FROM ONE PRODUCT IN
YOUR SUITE OF PRODUCTS. PLEASE ALSO ELABORATE IN YOUR MANAGEMENT'S
DISCUSSION AND ANALYSIS AS TO WHETHER YOU PLAN TO CONTINUE TO
SUBSTANTIALLY DERIVE YOUR REVENUE FROM THIS PRODUCT.

The prospectus has been revised to include the requested disclosure.

RISK FACTORS

WE ANTICIPATE THAT AN INCREASING PORTION OF OUR REVENUES WILL DEPEND..., PAGE
12

8. WE NOTE YOUR RESPONSE TO COMMENT 15 OF OUR LETTER DATED APRIL 13,
2006. DELL IS A SIGNIFICANT SELLER OF COMPUTER HARDWARE.
NOTWITHSTANDING YOUR RESPONSE THAT DELL HAS NO MINIMUM SALES
REQUIREMENTS OR MARKETING OBLIGATIONS, YOUR ARRANGEMENT WITH DELL
THROUGH YOUR AGREEMENTS AFFORDS YOU THE ABILITY TO HAVE YOUR SOFTWARE
OFFERED TO DELL'S LARGE CUSTOMER BASE. YOUR AGREEMENTS WITH DELL
CONSTITUTE 18 PERCENT OF YOUR REVENUE FOR THE NINE MONTHS ENDED
DECEMBER 31, 2005. ACCORDINGLY, IT APPEARS THAT YOU ARE DEPENDENT ON
YOUR ARRANGEMENT WITH DELL THROUGH YOUR AGREEMENTS FOR A SIGNIFICANT
PORTION OF YOUR REVENUE AND, AS A RESULT, SUCH AGREEMENTS ARE MATERIAL
PURSUANT TO ITEM 601(b)(10)(II)(B) OF REGULATION S-K. PLEASE FILE SUCH
AGREEMENTS OR FURTHER ADVISE US OTHERWISE.

The agreements have been filed as exhibits to the Registration Statement.

CREDIT SUISSE SECURITIES (USA) LLC, AN UNDERWRITER IN THIS OFFERING, HAS AN
INTEREST..., PAGE 23

9. PLEASE ELABORATE ON THE SPECIFIC RISKS TO THE OFFERING POSED BY THE
CONFLICT OF INTEREST OF CREDIT SUISSE SUCH AS ANY RISKS RELATING TO THE
PRICING OR EXECUTION OF THE OFFERING.

The prospectus has been revised as requested.

APPROXIMATELY % OF OUR OUTSTANDING COMMON STOCK HAS BEEN DEPOSITED...,
PAGE 23

10. PLEASE ELABORATE FURTHER HERE OR ELSEWHERE, AS APPROPRIATE, ON THE
CRITERIA, IF ANY, USED BY THE TRUSTEE IN DETERMINING WHETHER OR NOT TO
VOTE ON A MATTER.

The prospectus has been revised as requested.

Mayer, Brown, Rowe & Maw LLP

Securities and Exchange Commission
June 30, 2006
Page 4

CRITICAL ACCOUNTING POLICIES

STOCK-BASED COMPENSATION, PAGE 39

11. IN YOUR RESPONSE, YOU INDICATE THAT YOU CONSIDERED THE DISCLOSURE GUIDANCE
SET FORTH IN THE AICPA'S AUDIT AND ACCOUNTING PRACTICE AIDS (THE PRACTICE
AID). IT IS NOT CLEAR FROM EXISTING DISCLOSURE THAT YOU HAVE ADDRESSED HOW
YOUR STOCK-BASED COMPENSATION VALUATION REFLECTS THE BEST PRACTICE FOR
PRIVATELY HELD EQUITY VALUATION. PLEASE ADDRESS FOLLOWING:

- IN YOUR MANAGEMENT'S DISCUSSION AND ANALYSIS OF STOCK-BASED
COMPENSATION, DISCLOSE THE INTRINSIC VALUE OF OUTSTANDING VESTED AND
UNVESTED OPTIONS BASED ON THE ESTIMATED OFFERING PRICE AND THE
OPTIONS OUTSTANDING AS OF THE MOST RECENT BALANCE SHEET DATE
PRESENTED IN THE REGISTRATION STATEMENT.

Management's discussion and analysis of stock-based compensation includes the
requested disclosure. The remaining blanks will be completed prior to
circulation of a preliminary prospectus.

- IN YOUR MANAGEMENT'S DISCUSSION AND ANALYSIS AND NOTE 9, EXPAND YOUR
DISCLOSURE TO ADDRESS HOW EACH OF THE FACTORS YOU DISCLOSE
CONTRIBUTED TO THE DIFFERENCE BETWEEN THE FAIR VALUE AS OF THE DATE
OF EACH GRANT AND THE ESTIMATED OFFERING PRICE. YOUR DISCUSSION
SHOULD CLARIFY THE REASONS FOR ANY DIFFERENCE BETWEEN THE FAIR VALUE
AT EACH OPTION GRANT DATE AND THE ESTIMATED OPTION PRICE RANGE.

In lieu of solely relying upon its internal valuation model, CommVault solicited
the assistance of an unrelated third-party valuation specialist to prepare a
retrospective determination of fair value of its common stock underlying the
stock option grants since January 1, 2005. The retrospective determination of
fair value of CommVault's common stock utilized the probability weighted
expected returns ("PWER") method described in the AICPA Technical Practice Aid,
Valuation of Privately-Held-Company Equity Securities Issued as Compensation
("Practice Aid"). The valuations performed by the unrelated valuation specialist
are located behind Tab B in the binder of supplemental materials accompanying
this filing. In addition, the prospectus has been revised to include the
significant factors that contributed to the increase in the fair value of
CommVault's common stock at each grant date during fiscal 2006 leading up to a
potential initial public offering.

Under the PWER method, the value of common stock is estimated based upon an
analysis of future values for the enterprise assuming various future outcomes.
In CommVault's situation, the future outcomes included two scenarios: (i)
CommVault becomes a public company ("public company scenario") and; (ii)
CommVault remains a private company ("remains private scenario").

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Securities and Exchange Commission
June 30, 2006
Page 5

The "public company" scenario was based on the estimated mid-point of the
initial public offering price range and utilized a discount rate ranging from
20% to 25% based on the inherent risk of an investment in CommVault. Under the
"public company" scenario, the closer CommVault gets to an initial public
offering, the higher the probability assessment weighting is for that scenario.
CommVault used a 10% probability assumption for its January 2005 grants and this
percentage increased to 90% for CommVault's March 2006 grant as significant
milestones were achieved and as discussions with CommVault's investment bankers
increased as CommVault prepared for the initial public offering process.

Under the "remains private" scenario, the retrospective estimates of enterprise
value at each of the grant dates since January 2005 were based upon a
combination of the income approach and the market approach. CommVault applied
weights of 80% to the income approach and 20% to the market approach because
CommVault believes that the income approach is a better approximation of value.
Under the income approach, CommVault's enterprise value was based on the present
value of its forecasted operating results. In addition, the income approach used
discount rates ranging from 20% to 25% (as discussed above) as well as an EBITDA
terminal multiple based upon the EBITDA multiples of a comparable group of
publicly-traded companies engaged in lines of business similar to CommVault.
Under the market approach, CommVault's estimated enterprise value was calculated
based upon the revenue multiples of the same group of comparable companies
discussed in the income approach. The fair value of CommVault's common stock
under the "remains private" scenario was determined by reducing the total
estimated "remains private" enterprise value by the liquidation preferences of
CommVault's Series A through E cumulative redeemable preferred stock and the
conversion preferences of the Series AA, BB and CC convertible preferred stock
as well as a discount for lack of marketability assuming CommVault remains a
private company.

The prospectus has been revised to reflect the results of the retrospective
determination of fair value of CommVault's common stock. In summary, CommVault
recorded approximately $9.2 million in deferred stock-based compensation expense
and recognized compensation expense of approximately $1.1 million during fiscal
2006 related to stock options that were granted with an exercise price that was
below the fair value of CommVault's common stock on the date of grant.

SUPPLEMENTAL MATERIAL BINDER, TAB E

12. WE NOTE THE SUPPLEMENTAL INFORMATION PROVIDED IN TAB E, WHICH INCLUDES AN
INTEROFFICE MEMORANDUM THAT DISCUSSES THE VALUATION METHODOLOGY AND
ASSUMPTIONS USED TO FAIR VALUE THE COMPANY'S OPTION GRANTS. PLEASE PROVIDE
A COPY OF THE ACTUAL VALUATION ANALYSIS THAT INCLUDES YOUR REVENUE OR
EARNINGS PROJECTIONS AND THE LIST OF COMPARABLE COMPANIES USED BY THE
BOARD OF DIRECTORS TO DETERMINE THE FAIR VALUE OF YOUR COMMON STOCK FOR
EACH GRANT DATE. ALSO, CONFIRM TO US THAT YOUR REVENUE AND OPERATING
PROJECTION ASSUMPTIONS ARE CONSISTENT WITH INTERNAL PROJECTIONS THAT WERE

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Securities and Exchange Commission
June 30, 2006
Page 6

USED BY MANAGEMENT, PRESENTED TO THE BOARD OF DIRECTORS, PROVIDED TO YOUR
BANKERS AND UNDERWRITERS, AND/OR USED BY OTHER PARTIES.

A copy of the actual valuation analysis and a list of the comparable companies
used by the board of directors to determine the fair value of CommVault's common
stock at each stock option grant date is located behind Tab C in the binder of
supplemental materials accompanying this filing.

The revenue and operating projections used in CommVault's valuation analysis
were consistent with internal projections that were used by management and
presented to CommVault's board of directors. The revenue and operating
projections used in CommVault's valuation analysis were generally higher
(generated higher per share value) than those provided to bankers, underwriters
and other third parties.

13. CONFIRM TO US THAT COMPARABLE COMPANIES WERE USED FOR THE MARKET APPROACH
AT EACH VALUATION DATE AND TELL US HOW MANAGEMENT DETERMINED THAT THE
COMPANIES USED IN YOUR VALUATION WERE IN FACT COMPARABLE.

CommVault used comparable companies for the market approach at each valuation
date. Based on its knowledge of the storage and management software industry,
CommVault identified the population of direct competitors along with other
companies within the industry that offer somewhat similar products. CommVault
then analyzed the identified population, selecting a peer group of
publicly-traded companies that it believed to be most comparable in terms of
business operations, size, stage of development, prospects for growth and risk.

14. WE NOTE THAT THE FAIR VALUE OF YOUR COMMON STOCK AS OF JANUARY 2005, MAY
2005, JULY 2005 AND NOVEMBER 2005 AS DISCLOSED ON PAGE F-23 OF YOUR
PROSPECTUS DOES NOT AGREE TO THE INFORMATION DISCLOSED ON PAGE 2 IN TAB E
TO YOUR SUPPLEMENTAL MATERIAL. PLEASE EXPLAIN.

The fair value of CommVault's common stock disclosed in the materials located
behind Tab E to the supplemental materials that accompanied the May 3, 2006
filing was the per share value calculated from CommVault's valuation analysis.
CommVault's Board of Directors used this per share value as a basis for
determining the fair value of CommVault's common stock at each

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Securities and Exchange Commission
June 30, 2006
Page 7

stock option grant date. The difference between the per share value calculated
by CommVault's valuation analysis and the fair value of CommVault's common stock
determined by the Board of Directors is primarily due to the conservative
approach the Board of Directors utilized when establishing fair values in fiscal
2006. As a result, the Board of Directors generally set the exercise price of
stock options higher than the per share value calculated from CommVault's
valuation analysis. However, the fair value determined by the Board of Directors
since January 1, 2005 is now superseded by the retrospective determination of
fair value as discussed above in the response to the second bullet under Comment
11.

15. WE NOTE THAT YOU APPLIED A MARKETABILITY DISCOUNT RATE OF 15 PERCENT FOR
OPTIONS GRANTED ON JANUARY 2005, MAY 2005, JULY 2005 AND SEPTEMBER 2005.
PLEASE EXPLAIN TO US HOW YOU DETERMINED THAT THIS DISCOUNT RATE OF 15
PERCENT DEMONSTRATES AN OBJECTIVE DETERMINATION OF FAIR VALUE.

Determining the fair value of CommVault's common stock required making complex
and subjective judgments, particularly since there was no trading market for its
common stock at the time of the each stock option valuation. CommVault initially
based the fair value of its common stock on multiples of a comparable group of
publicly-traded companies in its market sector. CommVault then applied a 15%
marketability discount to the multiples used to value its common stock in
January 2005, May 2005, July 2005 and September 2005 based on a qualitative
analysis utilizing the guidance in the AICPA Practice Aid "Valuation of
Privately-Held-Company Equity Securities Issued as Compensation." In retrospect,
based on the valuations performed by the unrelated valuation specialist as
described in the second bullet under Comment 11, this 15% discount was
conservative as compared to the 35% discount rate utilized by the unrelated
valuation specialist.

The factors considered in the qualitative analysis to determine the size of the
marketability discount were:

- Prospects for liquidity

- Risks associated with its business

- Risks related to CommVault's products

- Concentration of ownership

- Uncertainty of value

16. IN PAGE 8 OF THE SUPPLEMENTAL MATERIAL BINDER, TAB E, YOU INDICATE THAT
"[T]HE MOST IMPORTANT FACTOR IN RECONCILING AND EXPLAINING THE
DIFFERENCE BETWEEN THE FAIR VALUES

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Securities and Exchange Commission
June 30, 2006
Page 8

OF [Y]OUR COMMON STOCK AND AN ESTIMATED IPO PRICE OF $7.00 PER SHARE IS
[Y]OUR ACHIEVEMENT OF ANTICIPATED EARNINGS IN Q4 FY 06 AND THE INCREASED
CONFIDENCE THAT OUTSIDE ANALYSTS AND UNDERWRITERS HAVE IN USING [Y]OUR
PROJECTED CY 07 PROJECTIONS FOR IPO VALUATION PURPOSE." YOU FURTHER
INDICATE THAT "[W]ITH THE BENEFIT OF HINDSIGHT, THE COMPANY BELIEVES THAT
USING THE MID-POINT OF THE ESTIMATED OFFERING RANGE OF $7.00 PER SHARE IS
AN OBJECTIVE DEMONSTRATION OF FMV FOR THE JANUARY, MARCH AND APRIL 2006
GRANTS." WE FURTHER NOTE, THAT YOU "USED A MARKETABILITY DISCOUNT RATE OF
20% FOR THE JANUARY 2006 GRANT, 15% FOR THE MARCH 2006 GRANT AND 10% FOR
THE APRIL 2006 GRANT GIVEN THE RISKS AND UNCERTAINTIES OF PROCEEDING WITH
AN IPO." EXPLAIN TO US THE OBJECTIVE EVIDENCE THAT SUPPORTS EACH DISCOUNT
RATE USED IN 2006. PLEASE NOTE THAT USE OF "RULE OF THUMB" DISCOUNTS IS
NOT AN APPROPRIATE METHOD OF ESTIMATING THE FAIR VALUE OF YOUR STOCK. SEE
FOOTNOTE 4 TO PARAGRAPH 4 OF THE PRACTICE AID.

As previously discussed, CommVault has prepared a retrospective determination of
the fair value of its common stock since January 1, 2005. As a result of that
analysis, CommVault's common stock valuation methodology utilizing discount
rates in fiscal 2006 has been superseded by a retrospective determination of
fair value of its common stock based upon valuations performed by an unrelated
valuation specialist. See the response to the second bullet under Comment 11
above.

17. PLEASE TELL US WHAT CONSIDERATION YOUR AUDITORS GAVE TO CONSULTATION WITH
THEIR NATIONAL OFFICE REGARDING YOUR STOCK VALUATION ACCOUNTING AND
DISCLOSURE.

CommVault has been informed that its auditors have consulted with their national
office regarding CommVault's stock valuation accounting and disclosure.

MANAGEMENT, PAGE 63

18. PLEASE ENSURE THAT YOUR DISCLOSURE CONFORMS TO THE REQUIREMENTS OF ITEM
401 OF REGULATION S-K. WE NOTE, FOR EXAMPLE, THAT MR. FANZILLI'S
DISCLOSURE DOES NOT APPEAR TO FULLY ACCOUNT FOR THE PAST FIVE YEARS WITH
RESPECT TO HIS BUSINESS EXPERIENCE.

The prospectus has been revised to provide the requested disclosure.

19. WE NOTE YOUR RESPONSE TO COMMENT 36 OF OUR LETTER DATED APRIL 13, 2006. IT
APPEARS THAT DISCLOSURE RELATING TO ITEM 404 OF REGULATION S-K HAS BEEN
MADE WITH RESPECT TO MEMBERS OF YOUR COMPENSATION COMMITTEE. ACCORDINGLY,
DISCLOSURE PURSUANT TO ITEM 402(j)(III) OF REGULATION S-K APPEARS
NECESSARY. PLEASE FURTHER ADVISE US OF ANY RELATIONSHIP THE COMPANY HAS
WITH FRANCISCO PARTNERS.

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Securities and Exchange Commission
June 30, 2006
Page 9

The prospectus has been revised to provide the requested disclosure. One of
CommVault's directors, Keith Geeslin, is a Partner of Francisco Partners.
CommVault does not have any additional relationships with Francisco Partners.

STOCK OPTION GRANTS IN LAST FISCAL YEAR, PAGE 69

20. PLEASE ADVISE US HOW YOU PLAN TO VALUE THE OPTIONS DISCLOSED PURSUANT
TO ITEM 402(c) OF REGULATION S-K. WE NOTE YOUR REFERENCE IN YOUR
RESPONSE TO COMMENT 37 OF OUR LETTER DATED APRIL 13, 2006 TO THE
MATERIALS REGARDING YOUR VALUATION PROCESS. WE SUGGEST THAT YOU USE
THE MIDPOINT OF YOUR OFFERING PRICE FOR PURPOSES OF ITEM 402(c) AS THE
USE OF THAT NUMBER WILL INFORM INVESTORS OF THE IMPACT OF THE OFFERING
ON THE HOLDERS OF THE OPTIONS. PLEASE SEE INSTRUCTION 7 TO ITEM
402(C), RELEASE NO. 34-32723 AND INTERPRETATION J.17 OF OUR JULY 1997
MANUAL OF PUBLICLY AVAILABLE TELEPHONE INTERPRETATIONS. OTHERWISE, YOU
SHOULD DISCUSS IN A FOOTNOTE THE VALUATION METHOD AND ASSUMPTIONS USED
AND IN DETERMINING THE FAIR MARKET VALUE OF THE OPTIONS IN ACCORDANCE
WITH INSTRUCTION 9 TO ITEM 402(c).

The prospectus will be revised to include the requested information prior to
circulation of a preliminary prospectus. The options disclosed pursuant to Item
402(c) of Regulation S-K will be valued using the mid-point of the offering
price range.

THE CONCURRENT PRIVATE PLACEMENT, PAGE 73

21. PLEASE ADVISE US WHERE SUCH PREEMPTIVE RIGHTS ARE SET FORTH. FURTHER, IT
APPEARS THAT THE AGREEMENT SETTING FORTH SUCH RIGHTS SHOULD BE FILED WITH
YOUR REGISTRATION STATEMENT PURSUANT TO ITEMS 601(b)(10)(i) AND (II)(A) OF
REGULATION S-K.

The referenced preemptive rights are set forth in agreements filed as exhibits
to the Registration Statement.

22. WE NOTE YOUR RESPONSE TO COMMENT 39 OF OUR LETTER DATED APRIL, 13,
2006. NOTWITHSTANDING YOUR DISCLOSURE HERE IN YOUR PROSPECTUS AS
OPPOSED TO ITEM 15 TO YOUR REGISTRATION STATEMENT ON THIS CONCURRENT
SALE OF UNREGISTERED SECURITIES, ITEM 701(d) OF REGULATION S-K REQUIRES
BRIEF DISCLOSURE OF "THE FACTS RELIED UPON TO MAKE THE EXEMPTION
AVAILABLE." ENSURE THAT THE INFORMATION REGARDING THE BASIS FOR YOUR
CONCLUSION OF THE AVAILABILITY OF THE EXEMPTION RELIED UPON CONVEYS
SPECIFIC INFORMATION THAT ADDRESSES EACH UNREGISTERED TRANSACTION IN
THE THREE-YEAR PERIOD. PLEASE MAKE SUCH DISCLOSURE HERE OR AS REQUIRED
IN ITEM 15 TO YOUR REGISTRATION STATEMENT.

The prospectus has been revised as requested.

Mayer, Brown, Rowe & Maw LLP

Securities and Exchange Commission
June 30, 2006
Page 10

FINANCIAL STATEMENTS

NOTE 2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

REVENUE RECOGNITION, PAGE F-9

23. WE NOTE YOUR RESPONSE TO COMMENT 50 OF OUR LETTER DATED APRIL 13, 2006 AND
YOUR REVISED DISCLOSURE WITH REGARDS TO YOUR REVENUE RECOGNITION POLICY
AND THE ROLLING 12-MONTH ANALYSIS YOU PERFORMED TO DETERMINE VSOE FOR YOUR
PCS. PROVIDE A COPY OF YOUR VSOE ANALYSIS. IF THE VSOE VARIES FROM
CUSTOMER TO CUSTOMER WITHIN DIFFERENT CLASSES, THEN TELL US HOW YOU
DETERMINED THAT YOU CAN REASONABLY ESTIMATE FAIR VALUE. TELL US HOW YOU
CONSIDERED PARAGRAPHS 10 AND 57 OF SOP 97-2 IN YOUR ANALYSIS.

A copy of CommVault's rolling 12-month VSOE analysis is located behind Tab D in
the binder of supplemental materials accompanying this filing.

In accordance with paragraphs 10 and 57 of SOP 97-2, CommVault has established
VSOE for each of its customer classes based on the price charged when the same
customer support element is sold separately. VSOE does not vary from customer to
customer within the same class. CommVault has followed consistent pricing
policies for all customers within each customer class. As a result, CommVault
uses the specific customer support pricing policies applicable to each customer
class to establish VSOE. CommVault updates its rolling 12-month VSOE analysis
throughout the fiscal year in order to demonstrate and validate VSOE for the
customer support element.

24. WE NOTE YOUR RESPONSE TO COMMENT 51 OF OUR LETTER DATED APRIL 13, 2006 AND
YOUR REVISED DISCLOSURE IN NOTE 2 WITH REGARDS TO VSOE FOR OTHER
PROFESSIONAL SERVICES. TELL US HOW OFTEN THE DAILY OR WEEKLY RATES HAVE
CHANGED DURING THE PERIODS PRESENTED AND PROVIDE US A LIST OF THE RATE
CHANGES DURING SUCH PERIODS.

CommVault has made no material changes to the daily and weekly rates during the
periods presented in the prospectus. A list of the daily and weekly rate changes
during each of the periods presented in the prospectus is located behind Tab E
in the binder of supplemental materials accompanying this filing.

NET INCOME (LOSS) ATTRIBUTABLE TO COMMON STOCKHOLDERS PER SHARE, PAGE F-11

25. WE NOTE YOUR RESPONSE TO COMMENT 54 OF OUR LETTER DATED APRIL 13, 2006 AND
YOUR REVISED DISCLOSURE IN NOTE 2. WITH REGARDS TO THIS INFORMATION,
PLEASE EXPLAIN THE FOLLOWING:

- YOUR RESPONSE INDICATED THAT YOU DETERMINED THE SHARES OF SERIES A,
B, C, D AND E PREFERRED STOCK AND SHARES OF SERIES AA, BB AND CC
PREFERRED STOCK

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Securities and Exchange Commission
June 30, 2006
Page 11

ARE PARTICIPATING SECURITIES DUE TO THEIR PARTICIPATION RIGHTS
RELATED TO CASH DIVIDENDS DECLARED TO THE COMMON STOCKHOLDERS.
PLEASE EXPLAIN THESE RIGHTS AND REVISE YOUR DISCLOSURES IN NOTES 7
AND 8 TO INCLUDE A DISCUSSION OF SUCH RIGHTS FOR EACH ISSUANCE
PURSUANT TO SFAS 129.

The prospectus has been revised to provide the requested disclosure.

The holders of CommVault's Series AA, BB and CC convertible preferred stock are
entitled to receive a proportionate share of cash dividends declared on
CommVault's common stock, calculated on an as if-converted basis. In addition,
the holders of CommVault's Series A through E cumulative redeemable convertible
preferred stock are entitled to receive dividends out of any assets legally
available, prior and in preference to any declaration or payment of any dividend
(payable other than in common stock or other non-redeemable equity securities
and rights entitling the holder to receive additional shares of CommVault's
common stock) on CommVault's common stock, at a per share rate of $1.788 per
annum, or, if greater, an amount equal to that paid on any other outstanding
shares of CommVault. Such dividends accrue and are cumulative.

In the event CommVault declares any other dividend or distribution payable in
securities of other persons, evidences of indebtedness issued by CommVault or
other persons, assets (excluding cash dividends) or options or rights to
purchase any such securities or evidence of indebtedness, holders of CommVault's
Series AA, BB and CC convertible preferred stock and Series A through E
cumulative redeemable convertible preferred stock are entitled to receive a
proportionate share of any such dividend or distribution on an as if-converted
basis. See the chart set forth in the response to the final bullet of this
Comment 25 for a full reconciliation of CommVault's basic earnings per share
calculation.

- PLEASE EXPLAIN WHY YOUR CALCULATIONS OF DILUTED EARNINGS PER SHARE
ON THE IF-CONVERTED METHOD FOR THE NINE MONTHS ENDED DECEMBER 31,
2005 DOES NOT INCLUDE THE DILUTIVE AFFECTS OF THE CONVERTIBLE
PREFERRED STOCK ON AN IF-CONVERTED BASIS. SEE ISSUE 6 TO EITF 03-6.

The prospectus has been revised to present diluted earnings per share under the
if-converted method, subject to the anti-dilution provisions of SFAS 128. To
reflect the maximum potential dilution, each series of issues of potential
common shares were considered in sequence from the most dilutive to the least
dilutive. As a result, in the nine months ended December 31, 2005 and the year
ended March 31, 2006, diluted net income (loss) attributable to common
stockholders per share presented under the if-converted method includes the
dilutive impact of CommVault's Series AA, BB and CC convertible preferred stock.
However, in the nine months ended December 31, 2005 and the year ended March 31,
2006, diluted net income (loss) attributable to common stockholders per share
presented under the if-converted method excludes the dilutive impact of
CommVault's Series A through E cumulative redeemable convertible preferred stock
because the conversion of such preferred stock in anti-dilutive to the diluted
earnings per share calculation.

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Securities and Exchange Commission
June 30, 2006
Page 12

- YOUR CALCULATIONS OF BASIC EARNINGS PER SHARE DO NOT APPEAR TO FIRST
REDUCE INCOME FROM CONTINUING OPERATIONS BY THE AMOUNT OF DIVIDENDS
DECLARED OR THE CONTRACTUAL AMOUNT OF DIVIDENDS DUE ON THE PREFERRED
STOCK. PLEASE EXPLAIN.

CommVault did not declare any dividends in the fiscal years ended March 31,
2004, 2005 and 2006. CommVault's calculation of basic earnings per share in the
fiscal years ended March 31, 2004, 2005 and 2006 does reduce net income by the
annual contractual amount of dividends of $1.788 per share due on the Series A
through E cumulative redeemable convertible preferred stock. See the chart set
forth in the response to the final bullet of this Comment 25 for a full
reconciliation of CommVault's earnings per share calculation.

- ALSO, TELL US WHY YOUR CALCULATIONS OF BASIC EARNINGS PER SHARE
UNDER THE TWO-STEP METHOD ALLOCATED A PORTION OF THE UNDISTRIBUTED
NET INCOME TO SERIES AA, BB AND CC PREFERRED STOCK AND NOT TO THE
SERIES A, B, C, D AND E PREFERRED STOCK. PLEASE PROVIDE THE SUPPORT
TO YOUR CALCULATIONS OF THE UNDISTRIBUTED EARNINGS.

The response to the first bullet point in this Comment 25 describes the
participating rights related to cash dividends of the Series A through E
preferred stock and Series AA, BB and CC preferred stock. Net income in the
basic earnings per share calculation is reduced by the contractual amount of
dividends ($1.788 per share) due on CommVault's Series A through E preferred
stock. Net income attributable to common stockholders is not allocated to the
Series A through E preferred stock because such stockholders only participate in
cash dividends in excess of their annual contractual dividend amount of $1.788
per share, and CommVault does not have the ability to distribute amounts in
excess of $1.788 per share in the year ended March 31, 2006.

The information required to compute basic net income (loss) attributable to
common stockholders per share is as follows (in thousands):

<Table>
<Caption>
YEAR ENDED MARCH 31,
2004 2005 2006
-------- -------- --------

RECONCILIATION OF NET INCOME (LOSS) TO UNDISTRIBUTED
NET INCOME (LOSS) ALLOCABLE TO COMMON STOCKHOLDERS
FOR THE BASIC COMPUTATION:
Net income (loss) $(11,698) $ 483 $ 10,756
Accretion of preferred stock dividends (1) (5,676) (5,661) (5,661)
-------- -------- --------
Net income (loss) attributable to common
stockholders (17,374) (5,178) 5,095
Undistributed net income allocated to Series
AA, BB and CC convertible preferred stock,
if converted (2) -- -- (1,730)
-------- -------- --------
Undistributed net income (loss) allocable to
common stockholders $(17,374) $ (5,178) $ 3,365
======== ======== ========
BASIC NET INCOME (LOSS) ATTRIBUTABLE TO COMMON
STOCKHOLDERS PER SHARE:
Basic weighted average shares outstanding 37,201 37,424 37,678
======== ======== ========
Basic net income (loss) attributable to common
stockholders per share $ (0.47) $ (0.14) $ 0.09
======== ======== ========
</Table>

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Securities and Exchange Commission
June 30, 2006
Page 13

(1) Net income is reduced by the contractual amount of dividends ($1.788
per share) due on CommVault's Series A through E cumulative
redeemable convertible preferred stock.

(2) In the year ended March 31, 2006, net income attributable to common
stockholders is reduced by the participation rights of the Series
AA, BB and CC convertible preferred stock related to cash dividends
declared by CommVault. Net income attributable to common
stockholders is not allocated to the Series A through E cumulative
redeemable convertible preferred stock because such stockholders
only participate in cash dividends in excess of their annual
contractual dividend amount of $1.788 per share, and CommVault does
not have the ability to distribute amounts in excess of $1.788 per
share in the year ended March 31, 2006. As a result, the detailed
calculation of CommVault's undistributed net income allocated to
Series AA, BB and CC convertible preferred stock is as follows (in
thousands except percentages):

<Table>
<Caption>
Weighted Average Shares Outstanding
------------------------------------------------------
Undistributed
Security Number of Shares Percentage of Total Earnings (3)
- ---------------------------------------- ------------------------------------------------------ ----------------------

Common Stock 37,678 66.0% $ 3,365
Series AA Preferred Stock 4,484 7.9% $ 400
Series BB Preferred Stock 2,758 4.8% $ 246
Series CC Preferred Stock 12,132 21.3% $ 1,084
------------------------------------------------------ ----------------------
19,374 34.0% $ 1,730
---------------------------
57,052
===========================
</Table>

(3) Undistributed earning is calculated as net income attributable to
common stockholders multiplied by the percentage of weighted average
shares outstanding.

26. WE NOTE YOUR RESPONSE TO COMMENT 55 OF OUR LETTER DATED APRIL 13, 2006
WHERE YOU INDICATE THAT YOU DID NOT CALCULATE THE FAIR VALUE OF YOUR
COMMON STOCK AS OF DECEMBER 31, 2005. WHAT VALUE DID YOU USE AT DECEMBER
31, 2005 AND HOW WAS SUCH VALUE DETERMINED? TELL US HOW YOU DETERMINED
THAT IT WAS APPROPRIATE TO EXCLUDE THE 2,030,000 SHARES SUBJECT TO STOCK
OPTIONS AND 4,615,000 SHARES SUBJECT TO WARRANTS FROM YOUR COMPUTATION OF
DILUTED NET INCOME ATTRIBUTABLE TO COMMON STOCKHOLDERS PER SHARE AT
DECEMBER 31, 2005.

The prospectus does not include financial statements for the nine months ended
December 31, 2005 because CommVault has updated the prospectus to reflect the
audited financial statements for fiscal 2006.

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Securities and Exchange Commission
June 30, 2006
Page 14

In connection with the preparation of the fiscal 2006 annual financial
statements, CommVault performed a retrospective determination of fair value of
its common stock underlying stock option grants since January 1, 2005 based upon
valuations performed by an unrelated valuation specialist. Based on this
analysis, CommVault determined that fair value of its common stock was $5.17 per
share on November 3, 2005 and CommVault used this per share value through
December 31, 2005 for the purposes of calculating diluted net income
attributable to common stockholders. CommVault has revised its earnings per
share calculation to reflect the retrospective determination of the fair value
of its common stock as described in CommVault's response to the second bullet in
Comment 11. As a result, no shares subject to stock options should have been
excluded from the earnings per share calculation at December 31, 2005. CommVault
has excluded 3,000,000 shares subject to warrants for the nine months ended
December 31, 2005 because the exercise price of such warrants ($6.27 per share)
exceeded the average fair value of CommVault's common stock of $4.96 for the
quarter ending December 31, 2005. In addition, no shares subject to stock
options have been excluded from the earnings per share calculation at March 31,
2006.

NOTE 7. CUMULATIVE REDEEMABLE CONVERTIBLE PREFERRED STOCK: SERIES A THROUGH E,
PAGE F-18

27. WE NOTE YOUR RESPONSE TO COMMENT 56 OF OUR LETTER DATED APRIL 13, 2006
WHERE YOU INDICATE THAT YOU BELIEVES THE KEY DETERMINANT IN EVALUATING THE
NATURE OF THE HOST INSTRUMENT IS THE ABSENCE OF A MANDATORY REDEMPTION
FEATURE. WHILE WE NOTE THAT THESE PREFERRED SECURITIES DO NOT HAVE A
MANDATORY REDEMPTION FEATURE, WE ALSO NOTE THAT YOU HAVE CLASSIFIED THE
SERIES A THROUGH E PREFERRED STOCK ISSUANCES IN THE MEZZANINE SECTION OF
THE BALANCE SHEET PURSUANT TO ASR 268 AND EITF D-98. CLASSIFICATION
OUTSIDE OF EQUITY INDICATES THAT THESE SECURITIES HAVE A REDEMPTION
FEATURE THAT IS OUTSIDE THE CONTROL OF THE COMPANY AND ALSO MAY BE AN
INDICATOR THAT THESE SECURITIES ARE MORE AKIN TO DEBT AS THEY HAVE A
MATURITY FEATURE, THAT WHILE IT MAY NOT BE MANDATORY, IT IS NOT WITHIN
YOUR CONTROL. PLEASE RECONCILE YOUR ANALYSIS OF ASR 268 AND EITF D-98 AND
YOUR DECISION TO CLASSIFY THESE SECURITIES OUTSIDE OF PERMANENT EQUITY TO
YOUR ANALYSIS OF PARAGRAPH 61(l) OF SFAS 133 WHERE YOU CONCLUDED THE
PREFERRED STOCK ISSUANCES WERE MORE AKIN TO EQUITY.

ASR 268 applies to all equity securities that are redeemable: (1) at a fixed or
determinable price on a fixed or determinable date, (2) at the option of the
holder or (3) upon the occurrence of an event that is not solely within the
control of the issuer. ASR 268 requires redeemable preferred stock to be
presented as a separate item outside of stockholders' equity. EITF Topic D-98
further clarifies the applications of ASR 268 and requires securities with
redemption features that are not solely within the control of the issuer to be
classified outside of permanent equity. Since the redemption of the Series A
through E cumulative redeemable convertible preferred stock is not solely within
the control of the holders or the issuer without regard to probability (the
Series A through E preferred stock is redeemable upon a qualified initial public
offering or upon approval of the Series AA and CC preferred stockholders, see
bullets below), CommVault has

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Securities and Exchange Commission
June 30, 2006
Page 15

classified such Series A through E preferred stock in the mezzanine equity
section of the balance sheet.

CommVault reviewed the guidance in paragraph 61(1) of SFAS 133 to determine if
such Series A through E preferred stock was more akin to equity (resulting in
mezzanine classification) or more akin to debt (resulting in liability
classification). Per paragraph 61(l) of SFAS 133, a typical cumulative
fixed-rate preferred stock that has a mandatory redemption feature is more akin
to debt, whereas cumulative participating perpetual preferred stock is more akin
to an equity instrument. CommVault believes these examples in SFAS 133 provide
two ends of a continuum in which neither properly describes CommVault's Series A
through E preferred stock. CommVault considered this guidance and believes its
Series A through E preferred stock is more akin to equity due to the following
features:

- The Series A through E preferred stock does not have a mandatory
redemption feature. Prior to a qualified initial public offering,
any election by the holders of such preferred stock to convert
shares into common stock and receive a cash payment of $14.85 per
share plus the aggregate amount of unpaid dividends requires the
approval of a majority of the Series AA and CC preferred stock, each
voting as a separate class. The Series A through E preferred
stockholders own approximately 15% of the Series AA and CC preferred
stock and accordingly cannot force the approval of redemption of the
Series A through E preferred stock.

- The Series A through E preferred stock do not contain a stated
maturity date. The Series A through E preferred stock is
contingently redeemable subject to the factors discussed above.

- Holders of shares of Series A through E preferred stock are entitled
to participate in dividends with common stockholders if a cash
dividend in excess of $1.788 per share of common stock is declared.

28. ALSO, YOU INDICATE THAT YOU ANALYZED THE CONVERSION FEATURE PURSUANT TO
PARAGRAPHS 12 THROUGH 32 OF EITF AND CONCLUDED THAT EQUITY CLASSIFICATION
WAS APPROPRIATE. PLEASE PROVIDE THE DETAILS TO YOUR ANALYSIS TO SUPPORT
YOUR CONCLUSIONS.

Since CommVault has determined that the Series A through E preferred stock is an
equity host, the embedded equity conversion feature does not require analysis
under paragraphs 12-32 of EITF 00-19. However, if additional analysis under EITF
00-19 were required, CommVault would conclude that the embedded derivative
should be classified as equity based on the following: 1) CommVault can issue
unregistered shares upon conversion of the preferred stock; 2) CommVault has
sufficient authorized and unissued shares available to allow for the conversion
of the preferred stock; 3) the conversion rights contain an explicit limit on
the number of shares to be delivered (conversion to common stock on a 4-to-1
basis); 4) cash payments to the holders of such preferred stock is not required
in the event CommVault fails to make a timely filing with the SEC; 5) the
conversion rights do not contain "top-off" or "make-whole" provisions; 6) there
are no net cash settlement provisions upon conversion; 7) the

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June 30, 2006
Page 16

conversion rights of the preferred stockholders do not rank higher than those of
the common stockholders in the event of CommVault's bankruptcy; and 8) there are
no requirements to post collateral at any point or for any reason.

NOTE 8. STOCKHOLDERS' DEFICIT, PAGE F-18

29. WE NOTE YOUR RESPONSE TO COMMENT 59 OF OUR LETTER DATED APRIL 13, 2006
WHERE YOU PROVIDE THE FAIR VALUE OF YOUR COMMON STOCK AT EACH MONTH IN
WHICH YOU ISSUED SHARES OF SERIES AA, BB AND CC PREFERRED STOCK. TELL US
HOW YOU DETERMINED SUCH VALUE FOR EACH ISSUANCE MONTH. SPECIFICALLY
EXPLAIN THE SIGNIFICANT FACTORS, ASSUMPTIONS AND METHODOLOGIES USED IN
DETERMINING THE FAIR VALUE. EXPLAIN THE SIGNIFICANT EVENTS THAT WOULD
ACCOUNT FOR THE DECREASE IN THE FAIR VALUE FROM NOVEMBER 2000 TO FEBRUARY
2002 AND THE FURTHER DECREASE IN SEPTEMBER 2003.

CommVault determined the fair value of its common stock in April 2000 and
November 2000 based on a contemporaneous valuation performed by an unrelated
third-party valuation specialist. The valuation specialist utilized a
combination of a guideline public company approach and discounted cash flow
approach (eight year model with terminal value) to estimate the fair value of
CommVault's common stock in April 2000 and November 2000.

CommVault believes that the fair value of its common stock in February 2002 was
equal to or less than $3.00 per share. CommVault estimated the fair value of its
common stock in February 2002 based on the $3.13 per share price of the initial
Series CC Preferred Stock that was primarily led by a new third-party investor
group. CommVault believes that the price for the Series CC preferred stock
should be higher than the fair value of the underlying common stock based on the
Series CC preferred stockholders' blocking rights if an initial public offering
does not provide a 2x return on their initial investment and the Series CC
preferred stockholders' liquidation preferences over the common stockholders in
the event of any liquidation or winding up of CommVault. In addition, the fair
value was further supported by a valuation performed by an unrelated third-party
valuation specialist in April 2001 which yielded a per share value of $2.90. The
valuation specialist utilized a combination of a guideline public company
approach and discounted cash flow approach (eight year model with terminal
value) to estimate the fair value of CommVault's common stock in April 2001. The
decrease in the fair value from November 2000 to February 2002 was primarily
associated with deteriorating marketing conditions in the storage and management
software industry, as well as the overall decrease in the Nasdaq composite of
approximately 33% during this time period.

CommVault believes that the fair value of its common stock in September 2003 was
equal to or less than $2.25 per share. CommVault was required to raise
additional funding in September 2003 through the issuance of a second round of
Series CC preferred stock. The second round of Series CC preferred stock was
priced consistently with the first round of Series CC preferred stock. CommVault
believes that the price for the Series CC preferred stock should be higher than
the fair value of the underlying common stock based on the Series CC preferred
stockholders' blocking rights if an initial public offering does not provide a
2x return on their

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Securities and Exchange Commission
June 30, 2006
Page 17

initial investment and the Series CC preferred stockholders' liquidation
preferences over the common stockholders in the event of any liquidation or
winding up of CommVault. In September 2003, CommVault estimated the fair value
of its common stock based on its analysis of comparable group of publicly traded
companies in its market sector. CommVault used the valuation methodology
contained in the memorandum included in the materials located behind Tab E to
the supplemental materials that accompanied the May 3, 2006 filing. CommVault
transitioned to this internal valuation methodology during fiscal 2004 because
it believed that its internal valuation model, which is built upon revenue and
earnings multiples of a comparable group of public companies, served as a
reasonable basis for establishing the fair value of its common stock. The
decrease in the fair value of CommVault's common stock from February 2002 to
September 2003 was primarily due to continued losses incurred by CommVault, the
inability to generate operating cash flows, the continuing challenge of being
able to accurately forecast revenue, and the continued difficulty of competing
as a smaller private company in a market that has historically been dominated by
larger public companies.

Should you have any questions regarding the foregoing or the amended
Registration Statement, please contact Philip Niehoff at (312) 701-7843 or Wendy
Gallegos at (312) 701-8057.

Very truly yours,
/s/ Wendy Gallegos
------------------
Wendy Gallegos

cc: Daniel Lee, Securities and Exchange Commission
Warren Mondschein, CommVault Systems, Inc.