[Qemu-devel] Re: [PATCH v2 2/2] rbd: allow configuration of rados from the rbd filename

[Stefan Hajnoczi <stefanha@gmail.com>]

On Thu, Apr 07, 2011 at 10:14:03AM +0900, Yoshiaki Tamura wrote:
> 2011/3/29 Josh Durgin <josh.durgin@dreamhost.com>:
> > The new format is rbd:pool/image[@snapshot][:option1=value1[:option2=value2...]]
> > Each option is used to configure rados, and may be any Ceph option, or "conf".
> > The "conf" option specifies a Ceph configuration file to read.
> >
> > This allows rbd volumes from more than one Ceph cluster to be used by
> > specifying different monitor addresses, as well as having different
> > logging levels or locations for different volumes.
> >
> > Signed-off-by: Josh Durgin <josh.durgin@dreamhost.com>
> > ---
> >  block/rbd.c |  119 ++++++++++++++++++++++++++++++++++++++++++++++++++--------
> >  1 files changed, 102 insertions(+), 17 deletions(-)
> >
> > diff --git a/block/rbd.c b/block/rbd.c
> > index cb76dd3..bc3323d 100644
> > --- a/block/rbd.c
> > +++ b/block/rbd.c
> > @@ -22,13 +22,17 @@
> >  /*
> >  * When specifying the image filename use:
> >  *
> > - * rbd:poolname/devicename
> > + * rbd:poolname/devicename[@snapshotname][:option1=value1[:option2=value2...]]
> 
> I'm not sure IIUC, but currently this @snapshotname seems to be
> meaningless; it doesn't allow you to boot from a snapshot because it's
> read only.  Am I misunderstanding or tested incorrectly?

Read-only block devices are supported by QEMU and can be useful.

Stefan