VSS snap shot warnings

Question

we keep getting warnings like this; 
 VSS Copy snapshot of '(Volume Labeled 'System Reserved'); C:\; X:\; P:\' on 'handa' was taken with excluded VSS writers 'System Writer {e8132975-6f93-4464-a53e-1050253ae220} has state 'FailedAtFreeze' and error 'WriterTimeout', WINS Jet Writer {f08c1483-8407-4a26-8c26-6c267a629741} has state 'FailedAtFreeze' and error 'WriterTimeout', FRS Writer {d76f5a28-3092-4589-ba48-2958fb88ce29} has state 'FailedAtFreeze' and error 'WriterTimeout', Shadow Copy Optimization Writer {4dc3bdd4-ab48-4d07-adb0-3bee2926fd7f} has state 'FailedAtFreeze' and error 'WriterTimeout', Registry Writer {afbab4a2-367d-4d15-a586-71dbb18f8485} has state 'FailedAtFreeze' and error 'WriterTimeout', NTDS {b2014c9e-8711-4c5c-a5a9-3cf384484757} has state 'FailedAtFreeze' and error 'WriterTimeout', WMI Writer {a6ad56c2-b509-4e6c-bb19-49d8f43532f0} has state 'FailedAtFreeze' and error 'WriterTimeout'' 
 
 on some of our servers, the above is a DC and this is our exchange box 
 VSS Full snapshot of 'C:\; L:\; S:\; G:\; R:\; E:\; (Volume Labeled 'System Reserved')' on 'harris' was taken with excluded VSS writers 'SqlServerWriter {a65faa63-5ea8-4ebc-9dbd-a0c4db26912a} has state '' and error ''' 
 and this is aSQL box 
 VSS Copy snapshot of '(Volume Labeled 'System Reserved'); C:\; D:\; S:\; L:\; Z:\' on 'RUM' was taken with excluded VSS writers 'System Writer {e8132975-6f93-4464-a53e-1050253ae220} has state 'FailedAtFreeze' and error 'WriterTimeout', SqlServerWriter {a65faa63-5ea8-4ebc-9dbd-a0c4db26912a} has state 'FailedAtFreeze' and error 'WriterTimeout', Shadow Copy Optimization Writer {4dc3bdd4-ab48-4d07-adb0-3bee2926fd7f} has state 'FailedAtFreeze' and error 'WriterTimeout', Registry Writer {afbab4a2-367d-4d15-a586-71dbb18f8485} has state 'FailedAtFreeze' and error 'WriterTimeout', WMI Writer {a6ad56c2-b509-4e6c-bb19-49d8f43532f0} has state 'FailedAtFreeze' and error 'WriterTimeout'' 
 
 it's mainly an annoyance as every thing seems to work ok but is it anything to worry about?? 
 
 cheers 
 
 Kerry

Tudor.Popescu · Answer

Hi Kerry: This is a big "no-no". VSS issues need to be investigated and fixed. You probably get "crash consistent" backups that contain incomplete or corrupt data. For instance, since the SQLwriter is disabled, the SQL data that is hosted in the memory (i.e. db table headers and pending transactions) is not flushed on disk before the backup. As a result, you may have backups with dbtable header corruption and incomplete records with missing dependencies similar with what you would get after a BSOD. When you restore, although the server boots up, you may not even notice the issues until much later. In my experience from my Sys Admin job (over 12 years), servers with minimal load have about 33% chances of not being affected by such backups. (One in three backups may be usable). On machines with moderate to high load the situation is much worse. If you add into equation that recovery points are rolled up (thus consolidated) and that if the SQLWriter is disabled, RapidRecovery has no idea about the dependencies between the logs volumes and database volumes (you are separating database and logs volumes, aren't you?), the predicted result is unusable backups. If you are not sure how to troubleshoot your VSS issues, I urge you to open a service ticket and we will help you out. Working in support, we have seen many avoidable cases when critical data and jobs (not only the poor backup guy's!) were on the line due to insufficient attention given to backup integrity!