[PVE-User] bad ZFS performance with proxmox 6.2

[Maxime AUGER]

Hello,

We notice a significant difference in ZFS performances between proxmox 5.3-5 and proxmox 6.2.
Last year when we tested proxmox5.3 on the HPE-DL360Gen9 hardware.
This hardware is provided with 8 ssd disks (2x 200-GB OS dedicated mdadm RAID0 and 6x 1-TB ZFS pool for VMs storage)
On ZFS pool we measured the peak value at 2.8GB/s (write)
Actually on promox6 we measured the peak value at 1.5GB/s (write).

One server, ITXPVE03 was running Initially on proxmox 5.3-5.
peak performance 2.8GB/s
Recently it has been reinstalled on proxmox 6.2 (from iso)
peak performance 1.5GB/s

to confirm this observation we have extended the checks to the 4 servers, identical hardware and low level software, BIOS and firmwares versions)
The measurements confirm the statement
All tests are done in serveurs idle state conditions with zero ative workload, all VMs/Containers shutdown.
ZFS configuration are identical, no compression, no deduplicatation

root at CLIPVE03(PVE6.2):~# dd if=/dev/zero of=/zfsraid10/iotest bs=1M count=1000
1000+0 records in
1000+0 records out
1048576000 bytes (1.0 GB, 1000 MiB) copied, 0.851028 s, 1.2 GB/s

root at ITXPV03(PVE6.2):~# dd if=/dev/zero of=/zfsraid10/iotest bs=1M count=1000
1000+0 records in
1000+0 records out
1048576000 bytes (1.0 GB, 1000 MiB) copied, 0.722055 s, 1.5 GB/s

root at CLIB05PVE02(PVE5.3-5):~# dd if=/dev/zero of=/zfsraid10/iotest bs=1M count=1000
1000+0 records in
1000+0 records out
1048576000 bytes (1.0 GB, 1000 MiB) copied, 0.397212 s, 2.6 GB/s

root at CLIB05PVE01(PVE5.3-5):~# dd if=/dev/zero of=/zfsraid10/iotest bs=1M count=1000
1000+0 records in
1000+0 records out
1048576000 bytes (1.0 GB, 1000 MiB) copied, 0.39394 s, 2.7 GB/s


At the ZFS level we can notice a difference in the version of zfsutils-linux
0.7.X on PVE5.3-5 (0.7.12)
0.8.X on PVE6.2 (same measure on 0.8.3 and 0.8.4)

has anyone experienced this problem ?

Maxime AUGER
Network Team Leader
AURANEXT