Andreas Nitsche
2009-Dec-03 07:46 UTC
[Xen-users] Xen DomU with high IOWAIT and low disk performance (lvm raid1)
Hello list! My setup: Dom0: Debain 5.0.3 with xen-hypervisor-3.2-1-i386 (2.6.26-2-xen-686) DomU: Ubuntu 8.04 2.6.26-2-xen-686 System is running on two hard drives mirrored with raid1 and organized by LVM. Dom0 and DomU are running on logical volumes. Partitions for DomUs are connected via ''phy:/dev/lvm/disk1,sda1,w'' for example. Here are some scenarios I testet, where you should easily can see that DomU is much much slower than Dom0 when having read and write access at the same time on the harddrive. dd if=/dev/zero of=test.img bs=1M count=1000 Dom0: $ dd if=/dev/zero of=test.img bs=1M count=1000 1000+0 Datensätze ein 1000+0 Datensätze aus 1048576000 Bytes (1,0 GB) kopiert, 12,88 s, 81,4 MB/s DomU: $ dd if=/dev/zero of=test.img bs=1M count=1000 1000+0 Datensätze ein 1000+0 Datensätze aus 1048576000 Bytes (1,0 GB) kopiert, 16,8728 s, 62,1 MB/s dd if=test.img of=/dev/null Dom0: $ dd if=test.img of=/dev/null 2048000+0 Datensätze ein 2048000+0 Datensätze aus 1048576000 Bytes (1,0 GB) kopiert, 5,47333 s, 192 MB/s DomU: $ dd if=test.img of=/dev/null 2048000+0 Datensätze ein 2048000+0 Datensätze aus 1048576000 Bytes (1,0 GB) kopiert, 10,2963 s, 102 MB/s Reading and writing from and to the hard drives works fast. date; cp test.img test2.img; date Dom0: $ date; cp test.img test2.img; date Do 3. Dez 08:22:44 CET 2009 Do 3. Dez 08:22:57 CET 2009 ~76,92 MB/s DomU: $ date; cp test.img test2.img; date Do 3. Dez 07:23:16 UTC 2009 Do 3. Dez 07:28:24 UTC 2009 ~3,25 MB/s date; mv test.img /backup/; date Dom0: $ date; mv test.img /backup/; date Do 3. Dez 08:28:45 CET 2009 Do 3. Dez 08:28:58 CET 2009 ~76,92 MB/s DomU: $ date; sudo mv test.img /backup/; date Do 3. Dez 07:31:15 UTC 2009 Do 3. Dez 07:36:16 UTC 2009 ~3,32 MB/s /backup is a second logical volume inside the same lvm. Each test was made time by time, so no process was running which produces high io at testing time. My question: Why is DomU that slow on read and write access at the same time? And how can I get that faster? -- regards Andi _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Andreas Nitsche
2009-Dec-03 11:08 UTC
Re: [Xen-users] Xen DomU with high IOWAIT and low disk performance (lvm raid1)
Hello, Problem is solved. After removing the sync option the partition in DomU is really fast. ~33 MB/s writing. -- Andi Am Donnerstag, den 03.12.2009, 08:46 +0100 schrieb Andreas Nitsche:> Hello list! > > My setup: > > Dom0: Debain 5.0.3 with xen-hypervisor-3.2-1-i386 (2.6.26-2-xen-686) > DomU: Ubuntu 8.04 2.6.26-2-xen-686 > > System is running on two hard drives mirrored with raid1 and organized > by LVM. Dom0 and DomU are running on logical volumes. > > Partitions for DomUs are connected via ''phy:/dev/lvm/disk1,sda1,w'' for > example. > > Here are some scenarios I testet, where you should easily can see that > DomU is much much slower than Dom0 when having read and write access at > the same time on the harddrive. > > dd if=/dev/zero of=test.img bs=1M count=1000 > Dom0: > $ dd if=/dev/zero of=test.img bs=1M count=1000 > 1000+0 Datensätze ein > 1000+0 Datensätze aus > 1048576000 Bytes (1,0 GB) kopiert, 12,88 s, 81,4 MB/s > DomU: > $ dd if=/dev/zero of=test.img bs=1M count=1000 > 1000+0 Datensätze ein > 1000+0 Datensätze aus > 1048576000 Bytes (1,0 GB) kopiert, 16,8728 s, 62,1 MB/s > > > dd if=test.img of=/dev/null > Dom0: > $ dd if=test.img of=/dev/null > 2048000+0 Datensätze ein > 2048000+0 Datensätze aus > 1048576000 Bytes (1,0 GB) kopiert, 5,47333 s, 192 MB/s > DomU: > $ dd if=test.img of=/dev/null > 2048000+0 Datensätze ein > 2048000+0 Datensätze aus > 1048576000 Bytes (1,0 GB) kopiert, 10,2963 s, 102 MB/s > > Reading and writing from and to the hard drives works fast. > > date; cp test.img test2.img; date > Dom0: > $ date; cp test.img test2.img; date > Do 3. Dez 08:22:44 CET 2009 > Do 3. Dez 08:22:57 CET 2009 > > ~76,92 MB/s > > DomU: > $ date; cp test.img test2.img; date > Do 3. Dez 07:23:16 UTC 2009 > Do 3. Dez 07:28:24 UTC 2009 > > ~3,25 MB/s > > date; mv test.img /backup/; date > Dom0: > $ date; mv test.img /backup/; date > Do 3. Dez 08:28:45 CET 2009 > Do 3. Dez 08:28:58 CET 2009 > > ~76,92 MB/s > > DomU: > $ date; sudo mv test.img /backup/; date > Do 3. Dez 07:31:15 UTC 2009 > Do 3. Dez 07:36:16 UTC 2009 > > ~3,32 MB/s > > /backup is a second logical volume inside the same lvm. > > Each test was made time by time, so no process was running which > produces high io at testing time. > > My question: Why is DomU that slow on read and write access at the same > time? And how can I get that faster? > > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xensource.com > http://lists.xensource.com/xen-users_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Dmitriy Sirant
2009-Dec-03 11:36 UTC
[Xen-users] Re: Xen DomU with high IOWAIT and low disk performance (lvm raid1)
03.12.09 13:08, Andreas Nitsche пишет:> Hello, > > Problem is solved. > > After removing the sync option the partition in DomU is really fast. ~33 > MB/s writing. >Hi, In which place you remove "sync" option ? Thank you _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Olivier B.
2009-Dec-03 11:53 UTC
Re: [Xen-users] Re: Xen DomU with high IOWAIT and low disk performance (lvm raid1)
Hi, in /etc/fstab I suppose. Olivier Dmitriy Sirant a écrit :> 03.12.09 13:08, Andreas Nitsche пишет: >> Hello, >> >> Problem is solved. >> >> After removing the sync option the partition in DomU is really fast. ~33 >> MB/s writing. >> > > Hi, > > In which place you remove "sync" option ? > > Thank you > > > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xensource.com > http://lists.xensource.com/xen-users_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users