Using KVM, its not always working

Yesterda I wrote about using KVM now on 2 servers. Just after I actually wrote that article I discovered KVM wasnt really working on one of these 2 servers (This server was just moved in, and is already a bit older as the other server. Its the old webserver kinda :)).

A first look it shows that everything works ok. However, when I start using it the performance is very bad with IO. After that by looking a bit around the VM was using IDE as driver for the VM. Nothing special, you think? I did actually think the same. Untill I did look at the config file at the other server, and discovered that the other server was using a complete other driver, called virtio for the harddisks at the server. Doing a fast google shows that virtio should provide a far higher performance, so this might be the reason.
After that I tried to actually use virtio at this server as well, but its just erroring out:

qemu: ‘file=/dev/vg0/backup,if=virtio,index=0′ unsupported bus type ‘virtio’

Nothing at google about the error, so no idea badly enough how to fix it. Myself I suppose its caused by this error in dmesg, however I have no idea why:P:

[ 32.705716] kvm: disabled by bios

Currently I don’t have yet a solution for this yet, and iam not sure what to do now. Just using the server without virtualisation? Should work, as its a old box, and only backups and some testing stuff will be on there. Or using xen at it? Both will do it probarly, but I need to think about it first :P

  1. Things can be easy sometimes » Paul's blog - pingback on 30 January 2010 at 14:07
  2. The error is because your CPU either doesn’t support VT; or it was not enabled in the bios. KVM will run with our VT but it’s much much slower, and as you’ve found doesn’t support some of the better features like virtio

    Nick
    Canhost.ca

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