WFC - Storage Replica - FileServer

[[OIT]Francis]

Hi, we are running a 4-node Fileserver role on a Windows Failover Cluster. We use StorageReplica to replicate data between the primary & secondary DC, this replication works as expected.
However, we are experiencing 'locks' every 4 hours (randomized within a few minutes) when something/some process is creating (trying) a VSS snapshot of all disks, including the "Disk_that_must_not_be_touched", which is the Replica LOG disk. Microsoft describes that this disk should not be targeted by backups or antivirus, and exclusions in the VEEAM backup process and our AV (SentinelOne) have been made.

First of all, I am not sure this is a VEEAM issue as the VSS snapshots happen outside of the backup window (which starts at 9 PM once daily), and it also does not conflict with configured Shadow Copies on the data disks. Via the GUI I see that Shadow Copies are NOT enabled on the Log disk. However, If I do a check with "vssadmin list shadowstorage" I see that storage is allocated for the logvolume (B:). I tried to delete all existing shadows for B: with "Vssadmin delete shadows /For=B: /all" but this throws the following error: "Error: Snapshots were found, but they were outside of your allowed context. Try removing them with the backup application which created them."

So ... to make it short. Is there anyone else using VEEAM Agent to backup a Windows Failover Cluster with Storage Replica enabled ? Does anyone know of a process in VEAAM Agent that might do a scan or VSS snapshot of all disks encountered every 4 hours (CBT Driver ?). I am trying to find out which task/process is creating those VSS snapshots, but I am at my wits end and cannot find the culprit.

Just to be clear, creating a snapshot of the B-disk (log) freezes the system (=documented by MS) and overtime will cause performance to drop and sometimes even a BSOD ... (all as documented by MS).

Thanks in advance for your advice/help.

[Dima P.]

Hello Francis.

VAW should not create snapshot for the volumes outside of the backup window, CBT drives does not create or lock snapshot as well, so that should not be the case.

I know that several customers were using VAW to protect files servers with such configuration, thus we got several improvement requests which are going to be implemented in upcoming version (automated exclusion of the log volume and exclusion for the mirror).

That said, I vote for opening a support case with our team to make sure that agent behaves correctly. If you do, please share the case ID in this thread. Thanks!