very slow disk ssd support all vms xcp-ng8.2.1

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i am going to upgrade to 8.3 and see if it fixed it but ssd performance is horrible and a full cr backup takes 15 hrs for a 400GB backup. strange thing if i run windows backup to a iscsi drive it backs up in 2 hrs. i cant find and reason why dive performance is so low but it can be faster for backups ect. if i image to a new drive it seems to get better for a bit but not long.its a hp z440 workstation .cpu load is low and all vms on macjine have low usage and cant find a reason for slow extream performance. thin provisioned ext.

any ideas ?
i have been using xcp for long time and cant figure this out.
running server 2022
windows update managed vm drivers.
This is after a backup finishes drive performance just tanks
first image is while running a 6gig compressing zip file inside vm

both are on same drives. about 400gig on 0% drive and 250 gig om other
the cant seem to find bottleneck

[olivierlambert]

Check the disk scheduler on the Dom0 for this drive.