Replication - VSS versus non VSS

[egroeg]

Hello all.

I am trying to run a replication to a LAN based ESX and in the wizard I select the option to enable "guess OS application" and enter my VSS domain admin credentials.

However, for some reason, out of 12 vms, I will always get one or two VMs that will fail with multiple varying errors (from vss asynchronous operation, freezing guest os, cannot create copy of vss writers data etc etc . . . )

If I change my replication job to not use VSS, then my replication is always successful.

Can someone please explain the pit falls of not using VSS aware replication - is it likely that the VSS method will be more repliable on a potential fail over?

Regards
Egro

[Alexey D.]

Hello George,

Please send the logs to our support team - it's simply impossible to name reasons for such errors across the forum.

If you replicate with VSS, that makes you be sure that VSS-aware applications inside guest OS are processed consistently, which is very important for high-transactional applications such as SQL Server, for example.

[Gostev]

I would recommend that you fix VSS framework issues, and re-enable application-aware processing. Depending on your Windows version, you may have to apply some Microsoft patches, as ealier Windows versions had some bugs in VSS framework. Our support should be able to assist in investigation and finding the root cause, but you may also end up having to open a support case with Microsoft since VSS framework is a part of Windows OS, and if something does not work correctly in it, there is little we could do from our side.

Generally speaking, Microsoft VSS framework is very reliable, and I rarely see customers reporting any failures associated with it.

[egroeg]

Ok, thanks gents.

I will enable the standard replication for the timebeing and investigate the errors for VSS replication individually (as each VM reports a slightly different issue).

Now confident that its a GuestOS issue / patching matter and can be resolved with a little TLC.

Thanks.

[tsightler]

Generally speaking, Microsoft VSS framework is very reliable, and I rarely see customers reporting any failures associated with it.

Agreed, but it can be very difficult to determine failure cases as there's almost no good troubleshooting info on the Microsoft side of things. We see about 1-2 VSS failures a night across our 75 VM's, but it's always one of the same 5 or 6 machines that report the issue, the others always work perfectly. There's very little in common between the machines that have problems though. We've been struggling with this especially since the new VSS in Veeam 5 as the failure cases have become much worse, especially if we configure Veeam to truncate logs only on success.

[Gostev]

Yep, I still owe you a reply on this when I get to the office... attending International Kickoff this week.