Re: [Xen-users] Is LVM really that much slower than Container?

["Fajar A. Nugraha" <fajar@xxxxxxxxx>]

On Mon, Apr 13, 2009 at 8:17 AM, Tim Kaufmann <tim@xxxxxxxxxxxxxx> wrote:
> Hi,
>
> I installed Windows XP SP3 to two domU. Only difference between them: one is
> stored in a container (let's call it domU1), while the other one (domU2) is
> stored on a logical volume made available by the dom0.
>
> I have a tar.gz-file which is 400 MB in size. Copying this file from a samba
> server on the network via LAN to domU1 takes 11 seconds on domU1 and a
> little more than 2 minutes on domU2.
>
> Creating a local copy of the file takes 3 seconds on domU1 and 80 seconds on
> domU2. Is that a penalty LVM-users have to live with or is something wrong
> with my system?

Could be cache effect. Since (when using file:/) the domU storage can
be cached in dom0, it will give the illussion of fast response when in
fact data has not been written yet. Does dom0 uses more than 400MB
memory (try xm list)?

It's not recommended to use file:/ as it's possible to cause data
corruption. Try changing it to tap:aio:/, and you should see that LVM
is faster.

Regards,

Fajar

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