SQL server & VSS

Question

Hi

Anyone know how to stop Networker perfoming operations on SQL server?

Background

Windows client with saveset attribute of all.

This is causing the following to occur (from SQL log)

00:40:56 Database c8_cs: IO is frozen for snapshot

00:40:57 Database c8_cs: IO is thawed

Apparently this is caused by VSS and the DBA doesnt want it to occur.

I can easily set the saveset attribute to explicit saveset - "C:\" in this case but would prefer not to.

Could disable VSS but if did that & left saveset attribute at "all" then assume the savegroup would then show a failure status.

Any help appreciated.

36115_carloscor · Answer

Hello Nicholas,

Looks to me as a known Microsoft issue. When backing up file system, it will try to backup also SQL files within the file system so, when those are being backed up, SQL writer freezes the DB temporarily. This is not because of Networker but because of SQL itself, so I would say maybe is better to have Microsoft answer about this.

Also you can check the SQL logs, and you will see logs such as "Legato..." and the time, which means that SQL DB has been backed up by Networker, but if you are getting any "NULL..." and the time, means that "something" it's interfering, and that's not Networker, so then you should definitely ask Microsoft.

As far as I know, even setting a directive to exclude those files it will still do the same. You can give it a try and let us know.

Create a directive to exclude SQL DB's and logs and see if the behavior is still the same.

Thank you.

Carlos.

36115_carloscor · Answer

Hi again nicholas,

Sorry I forgot to add the commands to check the SQL logs:

select name, backup_start_date

from msdb..backupset

where database_name = 'DBname'

order by backup_start_date desc

You only need to changce "DBname" for the actual namde of the DQ.

Thank you.

Carlos.

nicbone · Answer

Hi Carlos

Thanks for your quick responses - much appreciated.

To try to eliminate the issue I played the easy ball & set the saveset attribute for this backup client to explicit "c:\" (was "all"). This was to try to stop any VSS operations taking place & affecting the SQl instance.

Interestingly the freeze/thaw event still took place & the DBA still believes that it is the backup software causing this.

I have just now rerun the group with this client only & full verbosity & debug on. A freeze/thaw event still occurs although I see no mention of any VSS actions in the savegroup server side debug output. The command passed via savegroup is:-

build_ss_job(): Job command line: save -s ukmpsr3cnsr01 -g Croydon -LL -f - -m crosuatcog1 -t 1295690715 -l 9 -W 78 -N "C:\\" "C:\\"

So this is pretty interesting behaviour & does appear to be linked to Networker activity somehow.

Any thoughts?

We will look at disabling the Windows VSS service shortly to see if that changes things but it would be good to understand this behaviour in relation to the SQL server.

Nick

36115_carloscor · Answer

Hi Nicholas,

Just a quick test: Where are the SQL DB's and logs located? Have you tried to bakcup any other drive, which doesn't host any SQL related file? If so, are you seeing the same behavior?

Also, what is the OS, SQL version, and Networker version in Server and client?

Thank you.

Carlos.

nicbone · Answer

Hi Carlos

The SQL backup client is W2K3, SQL2000 and NW version was 7.4 The client only has interal disk "C:\"

I tried a few things this morning - added a directive to skip <<"C:\Program Files\Microsoft SQL Server\MSSSQL\data">>

Also from googling around added VSS:MSDEWriter=off to save operations under apps & modules for the client.

None of these worked with a freeze/thaw still occurring

HOWEVER

I upgraded the client NW software to 7.5sp3 (same as NW server) and it looks like this has worked. The previous changes outlined above were retained also.

thanks

Nick

NetWorker

SQL server & VSS

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