On 04/30/2012 06:48 PM, Eric Blake wrote: > On 04/30/2012 06:17 AM, Kashyap Chamarthy wrote: >> Hi (Eric?), >> >> I got a couple of questions for 'snapshot-create' / 'snapshot-create-as' : >> >> >> >> 1/ can '--disk-only' option (when used with virsh snapshot-create-as) be run on an offline >> guest and generate an 'external snapshot' ? > > Not yet, but it's on my list of things to add. > >> Or a running guest is needed? > > For now, this is true. > >> >> >> 2/ Can anyone point me to a bit more verbose info on these below options while creating >> snapshots? >> >> --quiesce quiesce guest's file systems >> --atomic require atomic operation >> --reuse-external reuse any existing external files > > http://libvirt.org/html/libvirt-libvirt.html#virDomainSnapshotCreateXML > > (Yuck - our online doc conversion loses paragraph breaks, and isn't > understanding how to mark up parameter names). > > --quiesce maps to VIR_DOMAIN_SNAPSHOT_CREATE_QUIESCE, which requests > that if the guest has a guest agent running, then connect to that agent > and request that the file systems be frozen before taking the snapshot > (that way, you can then directly boot the snapshot without having to run > fsck). I'm assuming you're talking about this 'agent' -- http://wiki.qemu.org/Features/QAPI/GuestAgent > > --atomic maps to VIR_DOMAIN_SNAPSHOT_CREATE_ATOMIC. If you are using > qemu 1.0 or earlier, this flag will fail unless you only snapshot a > single disk; if you are using qemu 1.1 or later, this flag will ensure > that the qemu monitor command 'transaction' is used to ensure an atomic > snapshot. Omitting the flag has no change of behavior on qemu 1.1, but > on qemu 1.0 or earlier, the snapshot is attempted, but if you fail > partway through, then you may be left with a domain where half the disks > had a snapshot and the other half did not. > > --reuse-external maps to VIR_DOMAIN_SNAPSHOT_CREATE_REUSE_EXT, which > states that rather than having libvirt create the snapshot file from > scratch, you will pre-create the file. This is useful for applications > like VDSM that want the snapshot to be pre-created with a relative > backing file name in the qcow2 metadata (libvirt would create it with an > absolute backing file name). > Thanks Eric, for the clarification and detailed info. -- /kashyap -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list