SQL Always On Error: VSSControl: Failed to freeze guest over network

[BennyDC]

Hi,

We have an SQL AWAYS On job that often get the following kind of errors

- Error: VSSControl: Failed to freeze guest over network, wait timeout
and
- Error: Failed to call RPC function 'Vss.Unfreeze': Error code: 0x80004005. Failed to invoke func [Unfreeze]: Unspecified error. Unfreeze error: [Backup job failed. Cannot create a shadow copy of the volumes containing writer's data. A VSS critical writer has failed. Writer name: [SqlServerWriter]. Class ID: [{a65faa63-5ea8-4ebc-9dbd-a0c4db26912a}]. Instance ID: [{d098991c-dc4b-4343-99c8-97e85da9dd87}]. Writer's state: [VSS_WS_FAILED_AT_PREPARE_SNAPSHOT]. Error code: [0x800423f4].]

last night we had back the
- Processing DECDC01PWSQS011 Error: VSSControl: Failed to freeze guest over network, wait timeout

The duration was more then 46min

We have currently 2 cases open for this 5223116 and 5219829

Out of a previous case that we changed
the following reg key
Go to registry key HKEY_LOCAL_MACHINE\SOFTWARE\Veeam\Veeam Backup and Replication
Add a DWORD (32-bit) value named VssPreparationTimeout. The value is in milliseconds (decimal), the default timeout is 900000, which equals 15 minutes. Set the value to 1800000. This will change the timeout to 30 minutes.
Stop any running jobs or wait for them to complete, then restart the Veeam Backup Service.

As this time we saw it failed after 46min what's higher then the 30min. My question is can we change without any issue this implemented reg key to an higher value?

On the always on servers we did also change the following values
(get-cluster).SameSubnetThreshold = 20 #(Default 10 in Windows 2012R2+)
(get-cluster).SameSubnetDelay = 2000 #(Default 1000 in Windows 2012R2+)
(get-cluster).CrossSubnetThreshold = 40 #(Default 20 in Windows 2012R2+)
(get-cluster).CrossSubnetDelay = 4000 #(Default 1000 in Windows 2012R2+)

Thanks for any advice

[Andreas Neufert]

Do you use Sophos antivirus?
veeam-backup-replication-f2/sql-vss-unf ... 49810.html

[BennyDC]

Hi Andreas no we are using Symantec Endpoint

[Andreas Neufert]

Yes, you can set it as well to higher value for the VSSPreparation.
But I would first check what I can do to process VSS faster. (This is general VSS and we just trigger it and are affected by it).
Make sure to implement Veeam KB1999 for correct Antivirus settings https://www.veeam.com/kb1999
As well make sure to be inline with the Microsoft Antivirus guidlines for SQL server: https://support.microsoft.com/en-us/top ... 51f6f3a95b
There are a lot of exclusions to be set.
I think it would be a good idea to check with Symantec if they have a guide for Microsoft SQL Antivirus protection.

[BennyDC]

Thanks Andreas
I did change the vss value.
Will check the exclusions in the docs but so far as I saw those are already in place.

[BennyDC]

Some extra use full information this always one server are having databases larger then 1TB.
Those databases are very busy