From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: [ANNOUNCE] Sheepdog: Distributed Storage System for KVM Date: Thu, 22 Oct 2009 11:28:59 -0500 Message-ID: <4AE0884B.9060603@codemonkey.ws> References: <4ADE988B.2070303@lab.ntt.co.jp> <4AE07A7F.8000002@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: MORITA Kazutaka , kvm@vger.kernel.org, qemu-devel@nongnu.org, linux-fsdevel@vger.kernel.org To: Avi Kivity Return-path: In-Reply-To: <4AE07A7F.8000002@redhat.com> Sender: kvm-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org 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