On 08/11/2011, at 2:22 AM, Avi Kivity <avi@xxxxxxxxxx> wrote:
> On 11/07/2011 03:57 PM, Peter Lees wrote:
>> hello all
>>
>> when trying to create a VM using a RAW image on a zfs filesystem, i get an
>> "invalid argument" error.
>>
>> has anyone made this work? is it a known issue and/or is there a workaround?
>>
>>
>>
>>
>> more detail:
>>
>> - i can create the VM on a ext4 filesystem
>> - i can create the VM on a ZFS zvol ("raw" device - too slow, however)
>> - linux is centos 6 (2.6.32-71.el6.x86_64 )
>> - zfsonlinux is v0.6.0 (http://zfsonlinux.org)
>> - qemu-kvm is v0.12.1.2 ; release 2.113.el6_0.8
>> - copying the VM disk from ext4fs to zfs & then running it results in a similar error
>>
>>
>> disk creation line was:
>>
>> # qemu-img create -f raw elveros_001.raw 15G
>>
>>
>> full error was:
>> Unable to complete install '<class 'libvirt.libvirtError'> internal error Process exited while reading console log output: char device redirected to /dev/pts/3
>> qemu: could not open disk image /space/vm_store/elveros_001.raw: Invalid argument
>
> I'm guessing that qemu tried to open the file with O_DIRECT, and
> zfsonlinux doesn't support O_DIRECT. Please try changing the cache mode
> to writeback.
>
>> any suggestions in getting ZFS as the vm_store, working with decent performance ?
>>
>
> zfsonlinux uses fuse, yes? I'd be surprised if you can get decent
> performance with it.
http://zfsonlinux.org
this is a source-release kernel module; it doesn't use fuse, and performance is ok for filesystem operations. no good at all for zvol operations, however.
thanks for the tip, i will give that a go
p
--
Peter Lees
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