Sophos Central Server causing VSS conflicts & backup errors

[DavR]

Hi all,

 

I've been investigating an intermittent bug with our backups, and I'm 90% sure that it's Sophos AV that's behind it. We're using Veeam, but the bug discussed covers any backup software that uses the Windows VSS writers.

 

Not every time, but now and then, one or two of our virtual machines fails to backup with the error "VSSControl: Failed to freeze guest over network, wait timeout". They'd then work just fine after a retry, which is why it's taken me a while to spot the fault.

 

It's been discussed extensively here, but looks like the Sophos Health Service is using VSS at the same time as Veeam tries to, causing a failure. There's a workaround described here which I'm currently testing, but thought I'd share for any other Sophos Central users on here who might be having backup issues.