KVM Disk Random I/O Speed

[matthew]

I have Proxmox 4.x installed on a 32gb RAM quad core box with a couple 4TB SATA drives installed using ZFS in raid 1 format.

How will the disk random I/O speed of a Centos 7 XFS KVM running under Proxmox compare to if it were on bare metal?

What I always liked about OpenVZ is there was not much difference but I need user quotas inside the container for Directadmin to work correctly and LXC does not offer it.

 

[LnxBil]

Do you want to compare ZFS->ZVOL->VM->XFS vs MD->XFS? Then of course XFS will win, yet you will not have the awesome features ZFS offers.

If you want to compare ZFS->ZVOL->XFS vs. ZFS->ZVOL->VM->XFS, this should yield similar performance values (yet of course slower, there is a longer I/O path) . Yet XFS (or anything else) on ZFS is always not optimal, because ZFS caches and the filesystem often caches too, so you have the same data maybe twice in your RAM.