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Re: [Qemu-devel] [RFC PATCH 1/1] ceph/rbd block driver for qemu-kvm
From: |
MORITA Kazutaka |
Subject: |
Re: [Qemu-devel] [RFC PATCH 1/1] ceph/rbd block driver for qemu-kvm |
Date: |
Fri, 21 May 2010 15:13:36 +0900 |
User-agent: |
Wanderlust/2.14.0 (Africa) SEMI/1.14.6 (Maruoka) FLIM/1.14.9 (Gojō) APEL/10.7 Emacs/22.3 (x86_64-pc-linux-gnu) MULE/5.0 (SAKAKI) |
At Fri, 21 May 2010 06:28:42 +0100,
Stefan Hajnoczi wrote:
>
> On Thu, May 20, 2010 at 11:16 PM, Christian Brunner <address@hidden> wrote:
> > 2010/5/20 Anthony Liguori <address@hidden>:
> >> Both sheepdog and ceph ultimately transmit I/O over a socket to a central
> >> daemon, right? So could we not standardize a protocol for this that both
> >> sheepdog and ceph could implement?
> >
> > There is no central daemon. The concept is that they talk to many
> > storage nodes at the same time. Data is distributed and replicated
> > over many nodes in the network. The mechanism to do this is quite
> > complex. I don't know about sheepdog, but in Ceph this is called RADOS
> > (reliable autonomic distributed object store). Sheepdog and Ceph may
> > look similar, but this is where they act different. I don't think that
> > it would be possible to implement a common protocol.
>
> I believe Sheepdog has a local daemon on each node. The QEMU storage
> backend talks to the daemon on the same node, which then does the real
> network communication with the rest of the distributed storage system.
Yes. It is because Sheepdog doesn't have a configuration about
cluster membership as I mentioned in another mail, so the drvier
doesn't know which node to access other than localhost.
> So I think we're not talking about a network protocol here, we're
> talking about a common interface that can be used by QEMU and other
> programs to take advantage of Ceph, Sheepdog, etc services available
> on the local node.
>
> Haven't looked into your patch enough yet, but does librados talk
> directly over the network or does it connect to a local daemon/driver?
>
AFAIK, librados access directly over the network, so I think it is
difficult to define a common interface.
Thanks,
Kazutaka
- [Qemu-devel] [RFC PATCH 1/1] ceph/rbd block driver for qemu-kvm, Christian Brunner, 2010/05/19
- Re: [Qemu-devel] [RFC PATCH 1/1] ceph/rbd block driver for qemu-kvm, Blue Swirl, 2010/05/20
- Re: [Qemu-devel] [RFC PATCH 1/1] ceph/rbd block driver for qemu-kvm, Avi Kivity, 2010/05/23
- Re: [Qemu-devel] [RFC PATCH 1/1] ceph/rbd block driver for qemu-kvm, MORITA Kazutaka, 2010/05/24
- Re: [Qemu-devel] [RFC PATCH 1/1] ceph/rbd block driver for qemu-kvm, Avi Kivity, 2010/05/24
- Re: [Qemu-devel] [RFC PATCH 1/1] ceph/rbd block driver for qemu-kvm, MORITA Kazutaka, 2010/05/24
- Re: [Qemu-devel] [RFC PATCH 1/1] ceph/rbd block driver for qemu-kvm, Avi Kivity, 2010/05/24
- Re: [Qemu-devel] [RFC PATCH 1/1] ceph/rbd block driver for qemu-kvm, Cláudio Martins, 2010/05/24
- Re: [Qemu-devel] [RFC PATCH 1/1] ceph/rbd block driver for qemu-kvm, MORITA Kazutaka, 2010/05/24
- Re: [Qemu-devel] [RFC PATCH 1/1] ceph/rbd block driver for qemu-kvm, Christian Brunner, 2010/05/24
- Re: [Qemu-devel] [RFC PATCH 1/1] ceph/rbd block driver for qemu-kvm, Anthony Liguori, 2010/05/24