Re: [Xen-users] Diskspace to DomU

[Tupshin Harper <tupshin@xxxxxxxxxxx>]

Jake Stevenson wrote:

> Hi,
>
> I am about to setup a new Xen server which will host a few DomU's, one
> of which will be a file server.
> The file server will, naturally, have quite a lot of disk space and my
> question is:
>
> If my file servrer domain uses a lot of disk space and the disks used
> are on two separate controllers, is it possible to dedicate those two
> PCI-devices to the domain and have that domain run LVM or EVMS to
> manage the disks itself instead of exporting a volume through Dom0?
>
> And if it is, which is best? Does it yield better performance this
> way, or should I stick with exporting it through Dom0?
>
> Oh, I have already used dedicated Ethernet NICs for a few domains so I
> now it is possible to assign PCI devices to privileged domains, so my
> first question is really if block devices is a "special case"
> which will not work.....
>
> Any input is appreciated.
>
> Best Regards
> Jake S.
>
FWIW, my approach for this was to export the raw devices that make up
the lvm to my fileserver domU and exclude (raid devices md2, md3, and
md4 in my case) them from /etc/lvm/lvm.conf in the dom0:
filter = ["r|/dev/md2|", "r|/dev/md3|", "r|/dev/md4|" ]

my domU disk config then looks like this:
disk = [ 'phy:xen_vg/fileserver,hda1,w',
         'phy:xen_swap_vg/fileserver,hda2,w',
         'phy:md2,sda2,w',
         'phy:md3,sda3,w',
         'phy:md4,sda4,w',
       ]

I haven't done any comparative benchmarks of this approach vs. any
other, but I haven't noticed any aggregiously bad performance from my
fileserver domU either.

-Tupshin

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