From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=51928 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Q7rsL-0006io-RT for qemu-devel@nongnu.org; Thu, 07 Apr 2011 12:16:06 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Q7rsK-00062P-MC for qemu-devel@nongnu.org; Thu, 07 Apr 2011 12:16:05 -0400 Received: from mail-iw0-f173.google.com ([209.85.214.173]:45469) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Q7rsK-00062J-JD for qemu-devel@nongnu.org; Thu, 07 Apr 2011 12:16:04 -0400 Received: by iwl42 with SMTP id 42so3194565iwl.4 for ; Thu, 07 Apr 2011 09:16:03 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: <6f9466b6098b5159aca9c789f9fce45f409e684f.1301354138.git.josh.durgin@dreamhost.com> <99252a76de350c8123eebfe4fc01fc6a1c9b2383.1301354138.git.josh.durgin@dreamhost.com> <20110407084707.GA21871@stefanha-thinkpad.localdomain> Date: Thu, 7 Apr 2011 09:16:02 -0700 Message-ID: From: Yehuda Sadeh Weinraub Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Subject: [Qemu-devel] Re: [PATCH v2 2/2] rbd: allow configuration of rados from the rbd filename List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Yoshiaki Tamura Cc: Stefan Hajnoczi , ceph-devel@vger.kernel.org, Josh Durgin , qemu-devel@nongnu.org, kvm@vger.kernel.org On Thu, Apr 7, 2011 at 2:54 AM, Yoshiaki Tamura wrote: > 2011/4/7 Stefan Hajnoczi : >> On Thu, Apr 07, 2011 at 10:14:03AM +0900, Yoshiaki Tamura wrote: >>> 2011/3/29 Josh Durgin : >>> > The new format is rbd:pool/image[@snapshot][:option1=3Dvalue1[:option= 2=3Dvalue2...]] >>> > Each option is used to configure rados, and may be any Ceph option, o= r "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 >>> > --- >>> > =A0block/rbd.c | =A0119 +++++++++++++++++++++++++++++++++++++++++++++= +++++-------- >>> > =A01 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 @@ >>> > =A0/* >>> > =A0* When specifying the image filename use: >>> > =A0* >>> > - * rbd:poolname/devicename >>> > + * rbd:poolname/devicename[@snapshotname][:option1=3Dvalue1[:option2= =3Dvalue2...]] >>> >>> 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. =A0Am I misunderstanding or tested incorrectly? >> >> Read-only block devices are supported by QEMU and can be useful. > > I agree. =A0My 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. Yehuda