On 05/21/2012 10:54 PM, Eric Blake wrote: > On 05/21/2012 02:59 AM, Kashyap Chamarthy wrote: > >>>> http://libvirt.org/formatsnapshot.html >>> >>> That page is live based on libvirt.git, and should be up-to-date with >>> the current implementation; although I would welcome improvements for >>> additional things to mention. >> >> I'd probably like to add some examples there for each different variant of >> snapshots just >> to give a practical idea for people referring that page. I'll try to do this >> over the weekend. >> >> You mentioned this page is live based on libvirt.git. Can I manually edit >> the examples >> section? Just ensuring I'm not messing up around. > > The web page only updates when we push your changes to the upstream > libvirt.git. You can play with your local copy of libvirt.git to your > heart's content (and run 'make' then browse the local contents using a > file:/// URL) all before posting your patch for review here, without > worrying about what will happen to the upstream documentation. Part of > the review process is making sure that your proposed html changes will > make sense when they go live.
Yeah I already have a local copy. Will post when I have detail. Thank you. > >>> >>> Do you have specific scenarios in mind? Propose a problem that you >>> think a snapshot would help, then ask questions on which APIs you would >>> use to solve that problem. >> >> Nothing specific in mind. Let me see if I can provide a bit more info. >> I'm testing snapshots in the context of working with FreeIPA project, where >> I have a test >> set-up w/ multiple guests, with subtle env. changes in them, interacting w/ >> each other. I >> need keep track of a clean state, a state with a particular env set-up, >> revert to a >> certain state, etc, often ending up with a tree of (internal)snapshots for >> each guest. >> >> I'm just exploring what kind of snapshots are most efficient for these >> scenarios. > > offline system checkpoint snapshots (which is basically a form of > internal disk snapshots) and online disk snapshots (external disk > snapshots, no VM state) are the fastest to create; but it is easier to > boot an offline system checkpoint (the disks are assumed to be in a > stable state when the guest goes offline) compared to a disk snapshot > (if you don't have a guest agent running to quiesce the guest I/O before > taking the snapshot, then the resulting snapshot may require an fsck to > be usable in the context of booting from that snapshot). Yeah, I'm leaning towards on-line disk snapshots. (as I don't care much about VM state at the moment). Thanks again for the detail > >> >>> >>> Do you understand the difference between the various snapshot flavors? >>> There's several orthogonal issues to be aware of, although not all >>> combinations are supported. >> >> I think I do understand to a certain extent. I previously had a discussion >> with you when I >> initially started off and captured the notes as a blog post -- >> http://kashyapc.wordpress.com/2011/10/04/snapshotting-with-libvirt-for-qcow2-images/ >> >> However, thanks for the nice summary below. >> > >>> >> >> I'll post more when I have a bit more clarity and more specifics on what I'd >> like to try. >> >> I'm a little hazy with the external snapshots as the combinations/tree of >> snapshots can >> get a bit complex . Though I do use the basic operation in my daily work >> flow, like: >> >> ===================== >> root@~$ virsh list >> Id Name State >> ---------------------------------------------------- >> 11 f17test running >> >> root@~$ >> ===================== >> root@~$ virsh domblklist f17test --details >> Type Device Target Source >> ------------------------------------------------ >> file disk vda /var/lib/libvirt/images/f17test.qcow2 >> >> root@~$ >> ===================== >> root@~$ virsh snapshot-create-as f17test cleanf17 cleanf17-box --diskspec >> vda,file=/var/lib/libvirt/images/snap-f17test.qcow2 --disk-only >> Domain snapshot cleanf17 created >> root@~$ >> ===================== >> root@~$ virsh snapshot-list f17test >> Name Creation Time State >> ------------------------------------------------------------ >> cleanf17 2012-05-14 00:02:54 +0530 disk-snapshot >> >> root@~$ >> ===================== >> >> Thanks for your response. >> >> > -- /kashyap -- libvir-list mailing list libvir-list@redhat.com https://www.redhat.com/mailman/listinfo/libvir-list
