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

[Brian Krusic <brian@xxxxxxxxxx>]

I've had the same experience using an onboard Intel RAID 1 (mirror)  
setup.
So I disable Raid and use ext3/xfs to get expected r/w times.  I just  
do a daily dump/xfsdump-restore/xfsrestore to my second disk to  
achieve some form of DR.
I thought it was my MB/Raid so I never bothered posting.

- Brian




On Feb 25, 2009, at 11:47 AM, Olivier B. wrote:

> I did some tests to on some servers ( time dd if=/dev/zero of=TEST  
> bs=4k count=512000 )
> First server : raid 1 hardware with a PCI 32bits 3ware card.
> dom0 (ext3) :    39MB/s
> domU (ext3) :     1.4MB/s !!!
> domU (ext4) :    40MB/s
>
> Second server : raid 1 software with 2 SATA disks
> dom0 (ext3) :     96MB/s
> domU (ext3) :     91MB/s
> domU (ext4) :     94MB/s
>
> Note : I use vanilla kernel on DomU.
>
> So :
> - I see a big write problem from domU on hardware raid
> - the writeback feature of ext4 seem to "erase" this problem
>
> Olivier
> DOGUET Emmanuel a écrit :
> > I have finished my tests on 3 servers. On each we loose some  
> > bandwidth with XEN. On our 10 platform ... We always loose some  
> > bandwidth, I think it's normal. Just the bench method who must  
> > differ?
> > I have made bench (write only) between hardware and software RAID  
> > under XEN (see attachment).
> > Linux Software RAID is always faster than HP Raid. I must try too  
> > the "512MB+Cache Write" option for the HP Raid.
> > So my problems seem to be here.
> >
> >
> > -------------------------
> > HP DL 380
> > Quad core
> > -------------------------
> > Test: dd if=/dev/zero of=TEST bs=4k count=1250000
> >
> >
> >
> >          Hardware     Hardware    Software     Software
> >           RAID 5         RAID 5      RAID 5       RAID 5
> >          4 x 146G       8 x 146G   4 x 146G     8 x 146G
> > dom0 (1024MB,
> > 1 cpu)     32MB        22MB        88MB (*)    144MB (*)
> >
> > domU ( 512MB,
> > 1 cpu)      8MB        5MB         34MB        31MB
> > domU
> > (4096MB,
> > 2 cpu)     --          7MB         51MB        35MB
> >
> >
> >
> > *: don't understand this difference.
> >
> >
> > This performance seems to be good for you?
> >
> >
> >
> >
> >          Best regards.
> >
> >
> >
> >
> >
> > > -----Message d'origine-----
> > > De : DOGUET Emmanuel
> > > Envoyé : mardi 24 février 2009 17:50
> > > À : DOGUET Emmanuel; Fajar A. Nugraha
> > > Cc : xen-users; Joris Dobbelsteen
> > > Objet : RE: [Xen-users] Re: Xen Disk I/O performance vs
> > > nativeperformance:Xen I/O is definitely super super super slow
> > >
> > > For resuming :
> > >
> > > on RAID 0
> > >
> > >         dom0: 80MB      domU:   56MB                    Loose: 30M
> > >
> > > on RAID1
> > >
> > >         dom0: 80MB      domU:  55 MB            Loose: 32%
> > >
> > > on RAID5:
> > >
> > >         dom0: 30MB      domU:   9MB                     Loose: 70%
> > >
> > >
> > >
> > > So loose seem to be "exponantial" ?
> > >
> > >
> > >
> > >
> > > > -----Message d'origine-----
> > > > De : xen-users-bounces@xxxxxxxxxxxxxxxxxxx
> > > > [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] De la part de
> > > > DOGUET Emmanuel
> > > > Envoyé : mardi 24 février 2009 14:22
> > > > À : Fajar A. Nugraha
> > > > Cc : xen-users; Joris Dobbelsteen
> > > > Objet : RE: [Xen-users] Re: Xen Disk I/O performance vs
> > > > nativeperformance:Xen I/O is definitely super super super slow
> > > >
> > > >
> > > > I have made another test on another server (DL 380)
> > > >
> > > > And same thing!
> > > >
> > > > I'm always use this test :
> > > >
> > > > dd if=/dev/zero of=TEST bs=4k count=1250000
> > > >
> > > > (be careful with memory cache)
> > > >
> > > >
> > > > TEST WITH 2 RAID 5 (include system on RAID 5, 3x146G + 3x146G)
> > > > ---------------------------------------------------------------
> > > >
> > > > dom0: 1GO, 1CPU, 2 RAID 5
> > > >
> > > >       rootvg(c0d0p1):         4596207616 bytes (4.6 GB)
> > > > copied, 158.284 seconds, 29.0 MB/s
> > > >       datavg(c0d1p1):         5120000000 bytes (5.1 GB)
> > > > copied, 155.414 seconds, 32.9 MB/s
> > > >
> > > > domU: 512M, 1CPU         on System LVM/RAID5 (rootvg)
> > > >
> > > >       5120000000 bytes (5.1 GB) copied, 576.923 seconds, 8.9 MB/s
> > > >
> > > > domU: 512M, 1CPU         on DATA LVM/RAID5 (datavg)
> > > >
> > > >       5120000000 bytes (5.1 GB) copied, 582.611 seconds, 8.8 MB/s
> > > >
> > > > domU: 512M, 1 CPU on same RAID without LVM
> > > >
> > > >       5120000000 bytes (5.1 GB) copied, 808.957 seconds, 6.3 MB/s
> > > >
> > > >
> > > > TEST WITH RAID 0 (dom0 system on RAID 1)
> > > > ---------------------------------------
> > > >
> > > > dom0   1GO RAM 1CPU
> > > >
> > > >       on system (RAID1):
> > > >       i3955544064 bytes (4.0 GB) copied, 57.4314 seconds, 68.9 MB/s
> > > >
> > > >       on direct HD (RAID 0 of cssiss), no LVM
> > > >       5120000000 bytes (5.1 GB) copied, 62.5497 seconds, 81.9 MB/s
> > > >
> > > > dom0   4GO RAM 4CPU
> > > >
> > > >
> > > >
> > > > domU:  4GO, 4 CPU
> > > >
> > > >       on direct HD (RAID 0), no LVM.
> > > >       5120000000 bytes (5.1 GB) copied, 51.2684 seconds, 99.9 MB/s
> > > >
> > > >
> > > > domU: 4GO, 4CPU  same HD but ONE LVM on it
> > > >
> > > >       5120000000 bytes (5.1 GB) copied, 51.5937 seconds, 99.2 MB/s
> > > >
> > > >
> > > > TEST with only ONE RAID 5 (6 x 146G)
> > > > ------------------------------------
> > > >
> > > > dom0 : 1024MB - 1CPUI (RHEL 5.3)
> > > >
> > > >       5120000000 bytes (5.1 GB) copied, 231.113 seconds, 22.2 MB/s
> > > >
> > > >
> > > > 512MB - 1 CPU
> > > >       5120000000 bytes (5.1 GB) copied, 1039.42 seconds, 4.9 MB/s
> > > >
> > > >
> > > > 512MB - 1 CPU - ONLY 1 VDB [LVM] (root, no swap)
> > > >
> > > >       (too slow ..stopped :P)
> > > >       4035112960 bytes (4.0 GB) copied, 702.883 seconds, 5.7 MB/s
> > > >
> > > > 512MB - 1 CPU - On a file (root, no swap)
> > > >
> > > >       1822666752 bytes (1.8 GB) copied, 2753.91 seconds, 662 kB/s
> > > >
> > > > 4GB - 2 CPU
> > > >       5120000000 bytes (5.1 GB) copied, 698.681 seconds, 7.3 MB/s
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > > -----Message d'origine-----
> > > > > De : Fajar A. Nugraha [mailto:fajar@xxxxxxxxx]
> > > > > Envoyé : samedi 14 février 2009 06:23
> > > > > À : DOGUET Emmanuel
> > > > > Cc : xen-users
> > > > > Objet : Re: [Xen-users] Re: Xen Disk I/O performance vs native
> > > > > performance:Xen I/O is definitely super super super slow
> > > > >
> > > > > 2009/2/13 DOGUET Emmanuel <Emmanuel.DOGUET@xxxxxxxx>:
> > > > >
> > > > > > I have mount domU partition on dom0 for testing and it's OK.
> > > > > > But same partiton on domU side is slow.
> > > > > >
> > > > > > Strange.
> > > > > Strange indeed. At least that ruled-out hardware problems :)
> > > > > Could try with a "simple" domU?
> > > > > - 1 vcpu
> > > > > - 512 M memory
> > > > > - only one vbd
> > > > >
> > > > > this should isolate whether or not the problem is on your  
> > > > > particular
> > > > > domU (e.g. some config parameter actually make domU slower).
> > > > >
> > > > > Your config file should have only few lines, like this
> > > > >
> > > > > memory = "512"
> > > > > vcpus=1
> > > > > disk = ['phy:/dev/rootvg/bdd-root,xvda1,w' ]
> > > > > vif = [ "mac=00:22:64:A1:56:BF,bridge=xenbr0" ]
> > > > > vfb =['type=vnc']
> > > > > bootloader="/usr/bin/pygrub"
> > > > >
> > > > > Regards,
> > > > >
> > > > > Fajar
> > > > _______________________________________________
> > > > Xen-users mailing list
> > > > Xen-users@xxxxxxxxxxxxxxxxxxx
> > > > http://lists.xensource.com/xen-users
> > _______________________________________________
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>
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