queue/rotational=1 for SSD on RAID controller


New Member
Oct 20, 2022

I have a proxmox host reporting SSDs as hard drives.
/sys/block/DEVICE/queue/rotational is returning 1 instead of the expected 0

Then in the VM it's naturally also returning 1.

I am pretty sure I can blame the RAID PERC controller on our old Dell r620 for this. (I don't have a choice now but to use this RAID controller as-is).
The RAID controller sees them properly as SSD though.
The SSDs are exposed as one Virtual Disk in RAID 1.

Would it be safe and beneficial in terms of performance/reliability to mark the device as SSD by setting that flag in udev both on the host and the VM?
I don't know if this is the case for PERCs too but unless you are actually offloading RAID work to them and leveraging disks that also have the larger sector size needed for the PERC to store checksums you are probably better off just using the PERC as a pure JBOD HBA and implementing RAID at a software level be it Linux RAID (mdadm) or ZRAID (ZFS) since hardware controllers (at least in the old days) write in a propriatary format to the disk adding another point of failure/difficulty in recovery processes (of course you should have backups etc. but being able to move/read your disks to other controllers/systems without having to have the PERC is nice).
Following up on this, I set the flag to 1 in the host and in the guest (via the option in proxmox UI to simulate SSD).
It works.
I was able to test want I wanted. Performance on this controller are still terrible though :)


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