The way to interpret that output is that the HEAD revision of "CentOS3" has about a 700MB delta from the previous snapshot (i.e. 700MB + 18G are used by this image and its snapshot). There probably should be an option in the rbd CLI to generate the full usage for a particular image and all of its snapshots. Right now the only way to do that is to perform a du on the whole pool. -- Jason Dillaman ----- Original Message ----- > From: "Bill WONG" <wongahshuen@xxxxxxxxx> > To: "Mihai Gheorghe" <mcapsali@xxxxxxxxx> > Cc: "ceph-users" <ceph-users@xxxxxxxxxxxxxx> > Sent: Thursday, January 28, 2016 6:17:05 AM > Subject: Re: Ceph + Libvirt + QEMU-KVM > Hi Mihai, > it looks rather strange in ceph snapshot, the size of snapshot is bigger than > the size of original images.. > Original Image actual used size is 684M w/ provisioned 20G > but the snapshot actual used size is ~18G w/ provisioned 20G > any ideas? > == > [root@compute2 ~]# rbd du CentOS3 -p storage1 > warning: fast-diff map is not enabled for CentOS3. operation may be slow. > NAME PROVISIONED USED > CentOS3 20480M 684M > [root@compute2 ~]# rbd du CentOS3@snap1 -p storage1 > warning: fast-diff map is not enabled for CentOS3. operation may be slow. > NAME PROVISIONED USED > CentOS3@snap1 20480M 18124M > == > qemu-img info rbd:storage1/CentOS3 > image: rbd:storage1/CentOS3 > file format: raw > virtual size: 20G (21474836480 bytes) > disk size: unavailable > cluster_size: 4194304 > Snapshot list: > ID TAG VM SIZE DATE VM CLOCK > snap1 snap1 20G 1970-01-01 08:00:00 00:00:00.000 > On Thu, Jan 28, 2016 at 7:09 PM, Mihai Gheorghe < mcapsali@xxxxxxxxx > wrote: > > As far as i know, snapshotting with qemu will download a copy of the image > > on > > local storage and then upload it into ceph. At least this is the default > > behaviour when taking a snapshot in openstack of a running instance. I > > don't > > see why it would be any different with qemu-kvm. You must use the rbd snap > > feature to make a copy on write clone of the image. > > > On 28 Jan 2016 12:59, "Bill WONG" < wongahshuen@xxxxxxxxx > wrote: > > > > Hi Simon, > > > > > > how you manage to preform snapshot with the raw format in qemu-kvm VMs? > > > > > > and i found some issues with libvirt virsh commands with ceph: > > > > > > -- > > > > > > 1) create storage pool with ceph via virsh > > > > > > 2) create a vol via virsh - virsh vol-create-as rbdpool VM1 100G > > > > > > problem is here.. if we directly create vol via qemu-img create -f rbd > > > rbd:rbdpool/VM1 100G, then virsh is unable to find the vol. - virsh > > > vol-list > > > rbdpool command is unable to list the vol, it looks such commands - rbd, > > > virsh and qemu-img creating images are not synced with each other... > > > > > > cloud you please let me know how you use the ceph as backend storage of > > > qemu-kvm, as if i google it, most of the ceph application is used for > > > OpenStack, but not simply pure qemu-kvm. as if setting up Glnace and > > > Cinder > > > is troublesome... > > > > > > thank you! > > > > > > On Thu, Jan 28, 2016 at 5:23 PM, Simon Ironside < sironside@xxxxxxxxxxxxx > > > > > > > wrote: > > > > > > > On 28/01/16 08:30, Bill WONG wrote: > > > > > > > > > > > without having qcow2, the qemu-kvm cannot make snapshot and other > > > > > > > > > > > > > > > features.... anyone have ideas or experiences on this? > > > > > > > > > > > > > > > thank you! > > > > > > > > > > > > > > I'm using raw too and create snapshots using "rbd snap create" > > > > > > > > > > Cheers, > > > > > > > > > > Simon > > > > > > > > > _______________________________________________ > > > > > > ceph-users mailing list > > > > > > ceph-users@xxxxxxxxxxxxxx > > > > > > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > > > > _______________________________________________ > ceph-users mailing list > ceph-users@xxxxxxxxxxxxxx > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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