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    |   xen-users
Re: [Xen-users] Performance of network block devices (iSCSI) 
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On 14/11/08, Javier Guerra wrote:
 
On Thu, Nov 13, 2008 at 5:58 PM, Simon Hobson <linux@xxxxxxxxxxxxxxxx> wrote:
 
 I've deliberately not put the iSCSI initiator in Dom0 as I want to run the
 absolute minimum in Dom0. Also, putting the iSCSI initiator in Dom0 makes it
 harder to move a VM to another host - having it in the DomU means that the
 VM can be moved without any config changes.
 
you should really try that.  the different nature of net- and
block-devices means that there are a lot less context switches per MB
transferred, and the point of acknowledging makes a huge difference in
latency sensibility.
 
OK, I've *finally* managed to scrounge another box to do some testing 
on. I've setup open-iscsi in Dom0 and performance seems to be a lot 
better - I'm getting about 20MB/s and the backup server isn't sat on 
99% wio :-) 
I have another question though ...
on this page http://wiki.debian.org/iSCSI/open-iscsi it says :
 You can then mount the new device, but under most situation, you 
will want to use LABEL= syntax in /etc/fstab (see e2label).
 
I assume this is because the device name can change across restarts. 
Since I'm not mounting the volume in Dom0, just passing it to the 
guest in a "disk = [ 'phy:v ..." line, any suggestions on the best 
way to deal with this ? 
--
Simon Hobson
Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed
author Gladys Hobson. Novels - poetry - short stories - ideal as
Christmas stocking fillers. Some available as e-books.
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