SecProbe.io

Mail Stop 4561
October 19, 2017

Brian Carolan
Vice President, Chief Financial Officer
Commvault Systems, Inc.
1 Commvault Way
Tinton Falls, NJ 07724

Re: Commvault Systems, Inc.
 Form 10-K for the Fiscal Year Ended March 31, 2017
Filed May 5, 2017
Form 10 -Q for the Quarter Ended June 30, 2017
Filed July 26, 2017
File No. 001-33026

Dear Mr. Carolan :

We have limited our review of your filing to the financial statements and related
disclosures and have the following comments.  In some of our comments, we may ask you to
provide us with information so we may better understand your disclosure.

Please respond to these comments within ten business days by providing the requested
information or advise us as soon as possible when you will respon d.  If you do not believe our
comments apply to your facts and circumstances, please tell us why in your response.

After reviewing your response to these comments, we may have additional comments.

Form 10 -Q for the Quarterly Period Ended J une 30, 2017

Notes to Consolidated Financial Statements (unaudited)

Note 2.  Summary of Significant Accounting Polices

Deferred Commissions Costs, page 8

1. It appears that a portion of your sales commissions is expensed upon delivery of the
software lice nse and a portion related to services is deferred . If so, please revise to clarify
how your amortizat ion expense reflects the transfer of the license and services to your
customer.  Refer to ASC 340 -40-35-1 and 340 -40-50-2(b).

Brian Carolan
Commvault Systems, Inc.
October 19, 2017
Page 2

 2. Please tell us, and revise to clarify  if appropriate,  whether additional sales commissions
are paid upon contract renewal and, if so, whether such amounts are commensurate with
the initial commissions.  Please also disclose how commissions paid for renewals are
considered in your fi ve year period of benefit  for the initial commission .  Finally, please
disclose the period of time over which you amortize commission costs related to contract
renewals  Refer to ASC 340 -40-35-1 and 340 -40-50-2(b).

Note 3.  Revenue, page 9

3. For sales made through your indirect distribution channels, please clarif y whether the
performance obligation of providing software licenses is satisfied upon shipment or when
the software is made available for download , to your indirect distribution partners or to
the e nd user.  Tell us how you considered the guidance  in ASC 606 -10-25-30 and ASC
606-10-55-58C in determining the  point in time at which you recognize revenue and
disclose any significant judgements made in evaluating when control is
transferred.   Refer to AS C 606 -10-50-19.

4. Please tell us w hy the standalone selling price  of software is typically estimated using the
residual approach and how you met one of the criteria in ASC 606 -10-32-34(c).  To the
extent you have determined the selling price for your software is highly variable ; please
provide a comprehensive, quantitat ive discussion of such variability to support your
conclusions.

We remind you that the company and its management are responsible for the accuracy
and adequacy of their disclosures, notwithstanding any review, comments, action or absence of
action by the staff.

You may contact Frank Knapp, Staff Accountant] at (202)  551-3805  if you have
questions regarding comments on the financial statements and related matters.  P lease contact me
at (202) 551 -3499  with any other questions.

Sincerely,

 /s/  Kathleen Collins

Kathleen Collins
Accounting Branch Chief
Office of Information Technologies
and Services