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>]

I have another information, I see this in a documentation:

"If starting a fully-virtualized domains (ie to run unmodified OS) there are 
also logs in /var/log/xen/qemu-dm*.log which can contain useful information. "

And in our 'slow' platform we have this type of log  /var/log/xen/qemu-dm*.log 

and this processes is running :

root      5671  0.0  0.1  75412  6324 ?        Sl   16:33   0:00 
/usr/lib64/xen/bin/qemu-dm -M xenpv -d 1 -domain-name dom-v1 -vnc 0.0.0.0:0 
-vncunused
root      6559  0.0  0.1  75412  6328 ?        Sl   16:33   0:00 
/usr/lib64/xen/bin/qemu-dm -M xenpv -d 2 -domain-name dom-v2 -vnc 0.0.0.0:0 
-vncunused

and not in "fast" platform! Strange no?


Configuration file is same ...

-------------------------------------------
name = "dom-v1"
uuid = "7d8cdbe4-6728-48fc-92db-baef9c70d7fd"
maxmem = 4096
memory = 4096
vcpus = 2
bootloader = "/usr/bin/pygrub"
on_poweroff = "destroy"
on_reboot = "restart"
on_crash = "restart"
vfb = [ "type=vnc,vncunused=1" ]
disk = [ 'phy:/dev/rootvg/bdd-root,xvda1,w',
'phy:/dev/rootvg/bdd-tmp,xvda2,w',
'phy:/dev/rootvg/bdd-user,xvda3,w',
'phy:/dev/rootvg/bdd-var,xvda4,w',
'phy:/dev/rootvg/bdd-swap,xvda5,w',
'phy:/dev/rootvg/bdd-oracle,xvda6,w',
'phy:/dev/rootvg/bdd-data,xvda7,w',
'phy:/dev/rootvg/bdd-backup,xvda8,w'
 ]
vif = [ "mac=00:22:64:A1:56:BF,bridge=xenbr0" ]
-------------------------------------------



>-----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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