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] xen & iSCSI

To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-users] xen & iSCSI
From: Daniel De Marco <ddm@xxxxxxxxxxxxxxx>
Date: Thu, 24 Sep 2009 14:13:22 -0400
Delivery-date: Thu, 24 Sep 2009 11:14:10 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
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/mailman/listinfo/xen-users>, <mailto:xen-users-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-users>, <mailto:xen-users-request@lists.xensource.com?subject=unsubscribe>
Sender: xen-users-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: Mutt/1.5.19 (2009-01-05)

I'm setting up xen (on centos 5.3) and I'm facing a weird performance
issue with iSCSI.

I attach the iSCSI targets to dom0 and if I use them from dom0 I obtain
good performance with simple dd tests (~100MB/s both reading and

I then use the block devices for the domU and if I repeat the same dd test
from within the domU the write performace is still good (~100MB/s), but
the read performance is cut in half (~55MB/s).

I tried changing several parameters like read_ahead and such, but I can
not obtain a good read performance in the domU.

Any idea?

Thanks, Daniel.

Xen-users mailing list

<Prev in Thread] Current Thread [Next in Thread>