Gluster users - Apr 2010 - mirrored glusterfs for virtual machine images?

Did anyone use mirrored glusterfs for storing virtual machine images, 
like qcow2?

Virtual machine images are typically large, ranging from a few GBs to 
hundreds of GBs.
Usually, they are mirrored with things like DRBD.


I was wondering if anyone uses gluster (in mirrored mode) for storing 
images of running virtual machines?


How resilient can we expect gluster to be when:

1) the host writing to glusterfs crashes,
2) one of glusterfs mirrors crashes.

Anyone with some experience here?


-- 
Tomasz Chmielewski
http://wpkg.org

Am 25.04.2010 23:05, Jon M. Skelton wrote:
> I'm currently doing this. Ubuntu 10.04 (beta) using glusterfs to mirror
> qcow2 KVM machine images. Works quite well. In both your crashing cases,
> things look much like when VM gets 'virsh destroy'. It's a
little rough
> on the filesystem contained within the machine image. I've had some
luck
> cleaning them up accessing the machine image filesystems via qemu-nbd:
Did you compare how much performance drops, versus bare metal?

I.e. run it in virtual guest, virtual host and the glusterfs server 
itself (if virtual host is a different server than at least one of 
glusterfs servers)?


time dd if=/dev/zero of=/bigfile bs=1M count=5000

time dd if=/bigfile of=/dev/null bs=64k


And drop caches between each run with:

echo 3 > /proc/sys/vm/drop_caches

-- 
Tomasz Chmielewski
http://wpkg.org