Hello all,

I've been working on a project where we occasionally get all sorts of weird Volsnap event id's such as Event ID 9, Event id 25 etc before even backup starts. I know from the fundamentals, in order for the requestor(backup software) to proceed successfully without displaying any open_file errors, a snapshot is required, but if the snapshot is failing due to aforementioned issues, should we contact Microsoft/Windows Team or the Backup vendor itself?

As per my understanding, any backup software is just a requester and doesn't hold any say in the 'VSS operations', but wanted to know the thoughts of this community and how we deal with all sorts of Volsnap issues.

Just to add, recent event id 9 denotes that we are getting an error during "IOCTL_FLUSH_AND_HOLD" step of VSS operation.

thanks in adv

Hi,

As you said any backup software is a requester. However third party backup software will add their own VSS writer or provider to do backup, so it still could be a third party related issue.

Above all let's focus on the Event 25 issue. What's the operation system are you using? If it is a Windows Server 2003, please try step 1 to install the hotfix 967551. If it is not, skip to step 2. 

1. Rollup update for the volsnap.sys driver in Windows Server 2003 http://support.microsoft.com/kb/967551
After 967551 hotfix is installed, you must change the value of the UseTopDownAlloc registry entry to 1 to resolve the Stop code 0x0000006B issue.
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\VolSnap\UseTopDownAlloc

2. Set value of MinDiffAreaFileSize
Registry path: HKLM\SYSTEM\CurrentControlSet\Services\VOLSNAP\MinDiffAreaFileSize

Compute a value that is five percent of the smallest shadow copy storage space on any one volume on the system.

Use the following guidelines to set the MinDiffAreaFileSize value: 
If you compute a value that is less than or equal to (<=) 600 megabytes (MB), set the MinDiffAreaFileSize value to 600. If you continue to receive event ID 25, incrementally increase the value until the value exceeds 3,000.
If you compute a value that is more than or equal to (>=) 3,000 MB, set the MinDiffAreaFileSize value to 3000.
If you compute a value that is between 600 MB and 3,000 MB, set the value of MinDiffAreaFileSize to the value that you computed.

If issue still exists, please help provide the result of "vssadmin list providers" and "vssadmin list writers".