This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
Home Products Support Community News


[Xen-users] Disk IO trouble in Xen

To: <xen-users@xxxxxxxxxxxxxxxxxxx>
Subject: [Xen-users] Disk IO trouble in Xen
From: Greg Hellings <greg.hellings@xxxxxxxxxxxx>
Date: Thu, 01 May 2008 16:32:56 -0700
Delivery-date: Thu, 01 May 2008 16:33:44 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxx
List-help: <mailto:xen-users-request@lists.xensource.com?subject=help>
List-id: Xen user discussion <xen-users.lists.xensource.com>
List-post: <mailto:xen-users@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-users>, <mailto:xen-users-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-users>, <mailto:xen-users-request@lists.xensource.com?subject=unsubscribe>
Sender: xen-users-bounces@xxxxxxxxxxxxxxxxxxx
Thread-index: Acir467h7XjvghfWEd2tIwAX8t0tvQ==
Thread-topic: Disk IO trouble in Xen
User-agent: Microsoft-Entourage/
I'm having terrible IO trouble with an image based domu

This is the performance on the Dom0
[root@localhost /]# hdparm -tT /dev/sda

 Timing cached reads:   3228 MB in  2.00 seconds = 1617.22 MB/sec
 Timing buffered disk reads:  174 MB in  3.02 seconds =  57.60 MB/sec

And this is the performance on the DomU
[root@localhost ~]# hdparm -tT /dev/xvda

 Timing cached reads:   3336 MB in  2.00 seconds = 1669.98 MB/sec
 Timing buffered disk reads:   26 MB in  3.13 seconds =   8.30 MB/sec

Is it normal for the performance difference to be so great?  I'm running
CentOS 5 and the DomU image is stored on a LVM ReiserFS formatted partition.

Here is the config for the DomU
name = "dddevdb"
uuid = "927f1e915813c2dec60c8f76c2716783"
maxmem = 3072
memory = 2042
vcpus = 2
bootloader = "/usr/bin/pygrub"
on_poweroff = "destroy"
on_reboot = "restart"
on_crash = "restart"
vfb = [ "type=vnc,vncunused=1,keymap=en-us" ]
disk = [ "tap:aio:/var/lib/xen/images/dddevdb.img,xvda,w"]
vif = [ "mac=00:16:3e:62:7a:d1,bridge=xenbr0" ]

Xen-users mailing list