[Sheepdog] general question about sheepdog operation (block distribution)

Liu Yuan namei.unix at gmail.com
Tue Nov 1 03:17:45 CET 2011

On 11/01/2011 01:06 AM, Matthew Law wrote:

> On Mon, October 31, 2011 4:18 pm, Miles Fidelman wrote:
>> Thanks guys.  (FYI - I currently run DRBD over a pair of nodes that each
> run md raid 10 - as I go to 4 nodes, I've  been looking at different
> ways of establishing a reliable storage environment that allows VMs to
> migrate.)
> I think I have a similar requirement.  We currently run customer VMs on
> Xen 3.4 host running a mixture of MD RAID and hardware RAID cards.  We
> haven't had a great experience with the I/O performance of standalone KVM
> VMs compared to Xen on the same hardware and a debian stable base, so at
> the moment we would like to aim for Xen with the VM images on 'some kind
> of clustered storage'.

Have you ever tried upstream KVM? AFAI, virtio-io in the KVM achieves
pratically the same performance as XEN, even better scalability in a
single host with multiple guests, from our some old tests about IO on

Anyway, it is not hard to implement a XEN device that redirect IO to
sheepdog cluster as previously discussed, but we have much more urgen
stuff to push into sheepdog and make it stable ready for production use.


> I have high hopes that we might be able to achieve this one day with xen,
> ganeti and sheepdog.  I am unsure of the pro's and con's of sheepdog over,
> say, Ceph or Gluster for such a use case but I do like the way that
> sheepdog works and it's relative simplicity (I really don't want to go
> anywhere near iSCSI or ATAoE ever again!).  If kvm's I/O issues can be
> isolated and fixed for our use case then for me it would come down to
> integrating sheepdog with ganeti.
> I am already looking at integrating sheepdog and ganeti as well as writing
> some test cases for sheepdog/collie but the workload on the run-up to
> Christmas is getting in the way a little.
> Cheers,
> Matt.

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