Re: [ANNOUNCE] Sheepdog: Distributed Storage System for KVM

Anthony Liguori
2009-10-22T16:29:00Z

Avi Kivity wrote:
> On 10/21/2009 07:13 AM, MORITA Kazutaka wrote:
>> Hi everyone,
>>
>> Sheepdog is a distributed storage system for KVM/QEMU. It provides
>> highly available block level storage volumes to VMs like Amazon EBS.
>> Sheepdog supports advanced volume management features such as snapshot,
>> cloning, and thin provisioning. Sheepdog runs on several tens or
>> hundreds
>> of nodes, and the architecture is fully symmetric; there is no central
>> node such as a meta-data server.
>
> Very interesting! From a very brief look at the code, it looks like
> the sheepdog block format driver is a network client that is able to
> access highly available images, yes?
>
> If so, is it reasonable to compare this to a cluster file system setup
> (like GFS) with images as files on this filesystem? The difference
> would be that clustering is implemented in userspace in sheepdog, but
> in the kernel for a clustering filesystem.

I'm still in the process of reading the code, but that's the impression
I got too. It made me think that the protocol for qemu to communicate
with sheepdog could be a filesystem protocol (like 9p) and sheepdog
could expose itself as a synthetic. There are some interesting
ramifications to something like that--namely that you could mount
sheepdog on localhost and interact with it through the vfs.

Very interesting stuff, I'm looking forward to examining more closely.

Regards,

Anthony Liguori