How much of an effect does the speed of the boot device have on performance of KVM and ZFS under Proxmox? My hunch is that once KVM and ZFS are started, they shouldn't need to access the drive they are installed on very often (except for ZFS writing snapshots), at least as long as I have sufficient memory (I plan to set aside 64 Gb for the host/zfs). Thus, my plan is to put root on mirrored HDDs, and use M.2/PCI drives for hosting the VMs. Is there any reason why I should worry about the performance of the root partition rather than just making sure it is big enough for the snapshots I want to keep?
Does root volume speed matter?
- Thread starter RudeRubbish
- Start date
Hi,
an good performance of the root disk is needed for swap (like you wrote - should not happens, but sometimes is used...) and for logging.
So normaly you don't need much performance for this. If your host is an ceph-mon-node you need an better performance for logging.
But I don't understand your zfs-snapshots?! Because if you have the snapshots on the root-pool, your VMs are also there, or not?
Udo
an good performance of the root disk is needed for swap (like you wrote - should not happens, but sometimes is used...) and for logging.
So normaly you don't need much performance for this. If your host is an ceph-mon-node you need an better performance for logging.
But I don't understand your zfs-snapshots?! Because if you have the snapshots on the root-pool, your VMs are also there, or not?
Udo
Thanks for the reply! I think I was misunderstanding where the snapshots are located. My plan is to have at least two separate pools though. I'll probably ask a question about snapshot storage at some point, but that's for another day.
Yes, that is my plan. Depending on how many VDEVs they end up having, I might split it further, because the fact that loss of a single VDEV kills the pool scares me and I'd like to compartmentalize the risk.
And what about copying files between VMs? Do these need to be cached in the host? I ask because VirtrualBox makes huge temp files on my C drive when I try to copy from a VM to a different third drive.