Proxmox . Replaced on some VMs virtual hard disks with IDE on VirtIO .

In the /etc/pve/qemu-server/*.conf files, /etc/pve/qemu-server/*.conf replaced these lines: bootdisk: virtio0 instead of ide0 :

 virtio0: local:105/vm-105-disk-1.qcow2,size=10G

The speed increase was pleasantly surprised. But on some machines, the speed has not changed:

 hdparm -t /dev/vda 768 MB in 3.00 seconds = 255.58 MB/sec

and

 hdparm -t /dev/sda 768 MB in 3.00 seconds = 260.58 MB/sec

which is almost the same.

On the same machines where everything became “beautiful”:

 hdparm -t /dev/vda 768 MB in 3.00 seconds = 760.58 MB/sec

I understand that the problem is in the VM itself. But for the time being I cannot understand why VM seems not to perceive that it works with a virtio driver. The machines have ubuntu server 12.04 LTS installed.

How to solve this problem?

  • all virtual disks are on the same real drive? - aleksandr barakin
  • Yes. All virtual disks are on the same real drive. - dobriivoin
  • hmm ... I haven't seen your question yet - I thought that I was fine ... On one installation of Proxmox (3.4-156), switching to virtio gave a noticeable speed increase. On the other (3.1-114) - there is no difference at all between scsi and virtio disks - Boris
  • one
    And what is the format of the virtual volume? qcow2 or raw? Perhaps it affects. Still, qcow's performance seems to degrade over time. - mmv-ru
  • virtual raw volume format. But the speed of the volume does not depend on this. I tried both formats on a test VM. This is not the problem. - dobriivoin

1 answer 1

I found the following hint on the forum: Type the drive as scsi, and in options specify the type of emulation scsi as virtio. those. the config will turn out similar:

 bootdisk: scsi0 scsi0: local:105/vm-105-disk-1.qcow2,size=10G scsihw: virtio-scsi-pci