RE: [Xen-users] Re: Xen Disk I/O performance vs native performance: Xen I/O is definitely super super super slow

["DOGUET Emmanuel" <Emmanuel.DOGUET@xxxxxxxx>]

        Oops sorry!

We use only phy: with LVM. PV only (Linux on domU,Linux form dom0).
LVM is on hardware RAID.

For the RAID my question was (I'm bad in English):

It's better to have :

*case 1*
Dom0 and DomU   on         hard-drive 1 (with HP raid: c0d0)

Or 

*case 2*
Dom0            on      hard-drive 1    (if HP raid: c0d0)
DomU            on      hard-drive 2    (if HP raid: c0d1)
 


I don't know if this is my problem but the 2 platform with slow IO in DomU use 
case 1.
Other who have good IO use case 2.

  Best regard.




-----Message d'origine-----
De : Fajar A. Nugraha [mailto:fajar@xxxxxxxxx] 
Envoyé : jeudi 12 février 2009 14:28
À : DOGUET Emmanuel
Cc : xen-users@xxxxxxxxxxxxxxxxxxx
Objet : Re: [Xen-users] Re: Xen Disk I/O performance vs native performance: Xen 
I/O is definitely super super super slow

On Thu, Feb 12, 2009 at 5:47 PM, DOGUET Emmanuel
<Emmanuel.DOGUET@xxxxxxxx> wrote:
> Dom0 have same speed on Older or New. only domU is x2 slower minmum. (with
> Oracle and dd ony 5Gb file)

You're not giving enough details.
- Do you use PV or HVM domU?
- what backend you use for domU's disk? file: ? tap:aio:? phy:?

I'm guessing you probably use tap:aio. Try using phy: (i.e. using disk
/ partition / LVM as domU backend storage)


> I must try it on the future platform... but it's necessary to have
> hard-drive/RAID only for dom0?

If I understand your question correctly, the answer is yes. Dom0
should handle all redundancy (be it hardware or software raid). You
don't need raid on domU if it's already done on dom0.

Regards,

Fajar

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