[SOLVED] Component-Based Servicing (cbs.log) causes all drive space to be consumed

Question

Because I've seen this question asked in many places and not answered, I thought I'd post my issue and resolution here.  I regard this as a Bug, but I'm not invested enough to deal with the support incident process.

I've had repeated instances where a Windows 7 x64 client runs out of hard drive space, and found that C:\Windows\TEMP is being consumed with hundreds of files with names following the pattern "cab_XXXX_X", generally 100 MB each, and these files are constantly generated until the system runs out of space.  Upon removing the files & rebooting, the files start being generated again.

I've found that this is caused by large Component-Based Servicing logs.  These are stored at C:\Windows\Logs\CBS.  The current log file is named "cbs.log".  When "cbs.log" reaches a certain size, a cleanup process renames the log to "CbsPersist_YYYYMMDDHHMMSS.log" and then attempts to compress it into a .cab file.

However, when the cbs.log reaches a size of 2 GB before that cleanup process compresses it, the file is to large to be handled by the makecab.exe utility.  The log file is renamed to CbsPersist_date_time.log, but when the makecab process attempts to compress it the process fails (but only after consuming some 100 MB under \Windows\Temp).  After this, the cleanup process runs repeatedly (approx every 20 minutes in my experience).  The process fails every time, and also consumes a new ~ 100 MB in \Windows\Temp before dying.  This is repeated until the system runs out of drive space.

This can be reproduced by trying to manually create the cab file -

 Directory of C:\CBS-BAK

08/26/2015  02:28 PM    <DIR>          .

08/26/2015  02:28 PM    <DIR>          ..

08/22/2015  09:12 PM     2,491,665,966 CbsPersist_20150823021618.log

C:\CBS-BAK>makecab CbsPersist_20150823021618.log

Cabinet Maker - Lossless Data Compression Tool

 86.19% - CbsPersist_20150823021618.log (1 of 1)

ERROR: (FCIAddFile)Data-size or file-count exceeded CAB format limits

C:\CBS-BAK>dir %TEMP%\cab*

 Volume in drive C is OSDisk

 Volume Serial Number is 44DE-0CDD

 Directory of C:\Users\USERNAME\AppData\Local\Temp

08/26/2015  02:31 PM       102,786,654 cab_4556_2

08/26/2015  02:28 PM                 0 cab_4556_3

08/26/2015  02:28 PM                 0 cab_4556_4

08/26/2015  02:28 PM                 0 cab_4556_5

08/26/2015  02:28 PM                 0 cab_4556_6

08/26/2015  02:28 PM        12,978,919 cab_5860_2

08/26/2015  02:27 PM                 0 cab_5860_3

08/26/2015  02:27 PM                 0 cab_5860_4

08/26/2015  02:27 PM                 0 cab_5860_5

08/26/2015  02:27 PM                 0 cab_5860_6

To resolve this -

Stop the Windows Modules Installer (TrustedInstaller) service

Delete or move the large Cbspersist_XX.log file out of \Windows\Logs\CBS.

Start the Windows Modules Installer (TrustedInstaller) service

Answer 1

If this problem keeps happening for you, it is likely some updates are failing to install and repeatedly retrying, causing the log to rapidly grow.  You would need to analyze the log content to determine which update(s) are failing and for what reason.

Answer 2

Cheers, I will check that out in more depth tomorrow.

Answer 3

Seems a lot of occurrences just recently.  Do you folk think that this is related to the Win10 1709 update?  It's a large update, an OS reinstall really, so it wouldn't suprise me for it to create a larger-than-usual cbs.log.

Your system may be having trouble with the upgrade, in which case the cbs.log may be a symptom rather than the cause.

To troubleshoot the installer issue, you would need to review ... The CBS.log file.

I know I'm having the same issue and my 1709 update has not successfully installed through auto updates and even when I download the update file from Microsoft and installed it manually. This is a new computer and the first time I decided to do a clean install to start fresh however its still hanging on that update and CBS file is out of control :( .

Answer 4

Check out the link in my earlier reply today. Follow the instructions and see if it works for you. I have a brand new notebook, too, and was ready to return it after about 4-5 days of frustration trying to get the updates to install. Those instructions worked great for me and the cbs.log was reduced back to a reasonable size, too.

Answer 5

Mine won't make it a month. Cleared out yesterday, and today already using up and additional 34 gb of allocated space. At this rate, I'm out of space again before Monday.

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