KVM disk passthrough and smart?

[zebrahost]

I am new to proxmox and this forum.

My user case is to establish new NAS on PROXMOX Server to save on footprint and power requirements.

Unfortunately my processor in proxmox host does not support PCI passthrough (iommu) so I have deployed a KVM Guest running Open Media Vault using disk passthrough to 2 x 4TB hard disks running a ZFS (via omv-extra's addon). Within the omv guest, I have successfully created the zfs pool which is operating as expected. I however noted that smart does not work and I dont know if power modes works either. I am currently using Virtio SCSI controller in the guest. I read that switching to standard SCSI controller (rather than Virtio SCSI) would enable smart to work, but my testing using a emulated LSI 53C895A controller did not resolve the issue.

Can you assist with any of the following questions?

What is disk passthrough anyway? Is there a white paper on it?
Is there a solution to getting smart working with disk passthrough?
Is doing zfs using disk passthrough a dumb idea? If so, what are my better alteratives?
proxmox offers native zfs itself, is there anyway I can leverage that rather than use disk passthrough without killing throughput or data integrity?
Is there a way to test if the power modes are working or otherwise?
Can the proxmox host do the smart testing as well as disk passthrough to the guest without creating conflicts with the guest (please note that I am not clear on how disk passthrough works so this is likely to be dumb question - apologies in advance)?

 

[wolfgang]

Hi,

What is disk passthrough anyway? Is there a white paper on it?

The same as normal paravirtual disks only use a disk instead of an image file.

Is there a solution to getting smart working with disk passthrough?

No

Is doing zfs using disk passthrough a dumb idea?

No because you have a dedicated disk.

proxmox offers native zfs itself, is there anyway I can leverage that rather than use disk passthrough without killing throughput or data integrity?

Yes, you can but if you use KVM you have no controller over it.
So snapshots are not possible in the OMV.
If you like performance and ZFS, I would recommend you LXC.

Is there a way to test if the power modes are working or otherwise?

Powersaving has to be done on the host with hdparm.

Can the proxmox host do the smart testing as well as disk passthrough to the guest without creating conflicts with the guest (please note that I am not clear on how disk passthrough works so this is likely to be dumb question - apologies in advance)?

Yes, you can use smartctl on the host.
The disk is controlled by the host and not the VM.