| |
|
 |
|
 |
|
|
|
| |
|
|
xen-users
Re: [Xen-users] Performance of network block devices (iSCSI)
Longina Przybyszewska wrote:
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 :-)
1. I wonder what test did you make to check performance?
I have the same concept with iscsi initiator directly on the domU
via bonding interface-->dedicated vlan on top of
bonding-->transparent bridge in Dom0-->DomU's eth1.
I would expect more advantages (performance, administration) with
iscsi-->DomU model.
I found that having the iSCSI initiator on DomU gave "poor"
performance (check the start of this thread). It's been suggested
that the single threaded model of Dom0 networking may be to blame.
Having the iSCSI on the DomU was my preferred setup as that would
allow me to shut down a guest, move it's config and storage to
another host, start it up and it would be just the same.
Performance was tested rather crudely with :
time ( dd if=/dev/zero of=testfile bs=1024k count=2048 ; sync )
this writes a file with 2GB of zeros, chosen to be larger than memory
available, and the sync makes sure we include the time taken to write
what does fit in memory.
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 ?
2. how can you pass the storage without mounting it/having access to, in Dom0?
Dom0 does have 'access' since it appears as a scsi drive (eg sdc,
with a partition sdc1). It is NOT mounted in Dom0, the device
(/dev/sdc1, or /dev/disk/by-id/...) is given to the DomU in the
"disk=" line. The DomU mounts it just the same as the rest of the
volumes given to it.
--
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.
_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-users
|
|
|
| |
|
Home