Hi again.
I'm really considering to move to a NAS solution. Any tip about which
disks (2.5 I suppose), rpms, manufacturer, NICs etc... of NAS devices?
Many thanks.
Javier
On 9 January 2014 07:45, Javi Legido <javi@xxxxxxxxxx> wrote:
> Hi Stefan.
>
> Many thanks for the tips. I already was doing all that you mentioned
> except LVM and raw files. Let me try this and let's see what happens.
>
> Thanks.
>
> On 9 January 2014 03:58, Stefan Hajnoczi <stefanha@xxxxxxxxx> wrote:
>> On Wed, Jan 08, 2014 at 10:51:16PM +0100, Javi Legido wrote:
>>> I'm experiencing bad performance on every I/O intensive action, such
>>> as clone a VM or when the guest updates packages via apt.
>>>
>>> I'm using a Directory pool [1] with qcow2 files since I like the
>>> ability to perform snapshots. Reading some literature looks like a
>>> Filesystem pool [2] plus raw disk images is the best combination in
>>> terms of disk performance.
>>>
>>> Can somebody please confirm or contradict?
>>
>> Usually LVM ('logical') offers the best disk performance. But at that
>> point you are working with logical volumes instead of regular files.
>> Some tools like backup applications may require regular files.
>>
>> If LVM doesn't suit your needs then raw image files do indeed offer the
>> good performance.
>>
>> Also try:
>>
>> * virtio-blk instead of IDE or SCSI
>> <target dev='vda' bus='virtio'/>
>>
>> * Linux AIO for local disks/files
>> <driver name="qemu" io="native" ... />
>>
>> * cache=none (O_DIRECT)
>> <driver name="qemu" cache="none" ... />
>>
>> If you still experience poor performance, please run a disk benchmark
>> (like fio) on both guest and host to compare performance. Make sure the
>> benchmark uses O_DIRECT to avoid the page cache.
>>
>> Stefan
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