[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

Thanks, I was able to remove the cbs.log now. I was hoping that was the cause of my problem with shutting down or restarting. This is where it takes hours to come back with the message:

"Getting Windows ready

Don't turn off your computer"

But, that didn't solve my real problem, that's still happening. I'll post another appropriate question about that when I get the computer up and running again.

Answer 2

Sme problem on my Ssd Samsung 840Evo after the update the cbs folder is 60gb

Answer 3

What in the world is going on?  I've had to delete my CBS.txt file twice now to free up space.  I still can't boot to the OS without losing my start button functionality.  If the recent MS update was the cause of this, I'd have to say its had the worst impact to my use of the OS in ~2 decades.

Answer 4

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.