2011/4/8 Yehuda Sadeh Weinraub <yehud...@gmail.com>: > On Thu, Apr 7, 2011 at 2:54 AM, Yoshiaki Tamura > <tamura.yoshi...@gmail.com> wrote: >> 2011/4/7 Stefan Hajnoczi <stefa...@gmail.com>: >>> On Thu, Apr 07, 2011 at 10:14:03AM +0900, Yoshiaki Tamura wrote: >>>> 2011/3/29 Josh Durgin <josh.dur...@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.dur...@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. >> >> I agree. My expectation was that @snapshotname is introduced to have >> writable snapshot. >> > The RADOS backend doesn't support writable snapshots. However, down > the rbd roadmap we plan to have layering which in a sense is writable > snapshots. The whole shift to librbd was done so that introducing such > new functionality will be transparent and will not require much or any > changes in the qemu code.
Thanks. It made things clear :) I think it's a good move. Yoshi > > Yehuda >
