Hey Checkyourlogs Fans,

I have been recently troubleshooting some slow backups from a new Storage Spaces Direct Cluster at a customer site. Have a look at the backup speeds from the backups before I started.


I was moving around a lot of data to the cluster and one thing I noticed was that when I start an SMB File copy from a cluster node to itself the speeds aren’t great. For example, I want to seed an ISO repository so I logged into the Storage Spaces Direct node opened C:\ClusterStorage\Volume1\ISO and tried copying some files over the network.

The maximum speed I was able to get was about 110 MB /sec over a 10 GB network. That should have been more like 500 MB /sec +.

Then I tried pushing the files from a remote server into \\S2D1\C$\ClusterStorage\Volume1\ISO and I got the full line speed of 500 MB /sec. I’m not sure if this has something to do with the CSVFS (Cluster Shared Volume File System) or some filter drivers directly on the node.

When I saw this issue on my Veeam farm it got me thinking that what if the On Host Proxy is slowing down the backups. So I tried moving it off the cluster to another Hyper-V Host that was a Replica Target on the same subnet.

And to my amazement copy speeds now look like this for the backups.

I captured the screen shot at the slow point as you can see I peaked around 500 MB / sec halfway through the job.


185 MB /sec is a lot better that 40-80 MB/sec which was what I was getting before.

Here is the change that I made on the Backup Job that helped me out.


I changed to Off-Host Proxy, and it seemed to make a big difference. I know of a lot of customers that have been struggling with VDI Deployments and the provisioning of VM’s being slow in VMM on a Storage Spaces Direct cluster. I’m starting to think that maybe if they put their VMM Server off the cluster and pushed the files to the CSV it would improve things a lot.

More testing to do I know à I just found this interesting enough that I wanted to share.

Hope this helps you on your journey with Veeam and Hyper-V.