My VMs freeze and corrupt on high disk I/O


New Member
Jul 21, 2019
I am having a disk problem with Proxmox. I'm running two SATA 2TB hard drives connected in a RAID 1 ZFS. I'm running Proxmox 5.4-3 on an R710.
Sometimes, but not always, high disk I/O starts breaking things. For example, last night I was doing a disk import, which was causing my I/O delay to be around 15%. When the nightly backup started, the combination of I/O from both made it so the VMs couldn't use the disk. Some of these VMs were just debian servers that weren't even doing anything, yet I couldn't log into them because of disk bottleneck. On the disk I/O graph for the individual VMs, I can see usage drop to exactly 0.
After a few minutes of this, the VMs started to corrupt. Some complained about errors writing to the disk, and some said they hit a 120s timeout when accessing I/O. After a reboot, some VMs needed a manual fsck, but all needed an automatic one. This process repeated a few times before I decided to cancel the backup and the import(cancelling just the backup did not help)
Curious about what I can do about this for the future. I would prefer it if proxmox could handle high disk activity a little more gracefully!
I don't think that's the problem - I'm using an HBA and ECC memory.

Either your HBA is wrong for ZFS/buggy or your RAM is faulty. At least, that is the case almost all of such issues.


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