Hello On 11 Apr 2014, at 8:52 am, Eric Blake <eblake@xxxxxxxxxx> wrote: [ … ] > >>>> # virsh snapshot-info host1 --current >>>> Name: snap1-host1 >>>> Domain: host1 >>>> Current: yes >>>> State: shutoff >>>> Location: internal >>> > >> # virsh snapshot-dumpxml host1 snap1-host1 >> <domainsnapshot> >> <name>snap1-host1</name> >> <description>After install completed</description> >> <state>shutoff</state> >> <creationTime>1390111150</creationTime> >> <memory snapshot='no'/> >> <disks> >> <disk name='vda' snapshot='external'> > > Okay, we've definitely demonstrated a bug in at least 'virsh > snapshot-list' for that particular build of libvirt; this proves that > the snapshot is definitely external, even though the info output claimed > it was internal. I didn't search whether a bugzilla entry was already > tracking this for RHEL 6.5; it's not a crasher, so it probably won't get > fixed until RHEL 6.6. If you'd like, you can open a BZ, (it might get > closed as a dup if someone else finds where it was already reported, > even though I didn't do that search), to make sure it doesn't get lost Thanks I’ll sort out getting bugzilla report put it. But will search it first. > Meanwhile, creating external snapshots is supported in that version of > RHEL, but not deleting (at least not via virsh directly), so you'll have > to get your hands a bit dirty with qemu-img and virsh edit. > >> <driver type='qcow2'/> >> <source file='/var/lib/libvirt/snap1-host1.qcow2'/> > > This says that snap1-host1.qcow2 is the wrapper file created at the time > of the snapshot, and that... > >> </disk> >> <disk name='vdb' snapshot='external'> >> <driver type='qcow2'/> >> <source file='/var/lib/libvirt/snap1-host1-db.qcow2'/> >> </disk> >> <disk name='hdc' snapshot='no'/> >> </disks> >> <domain type='kvm'> > ... >> <devices> >> <emulator>/usr/libexec/qemu-kvm</emulator> >> <disk type='file' device='disk'> >> <driver name='qemu' type='raw' cache='none'/> >> <source file='/var/lib/libvirt/images/host1.img'/> > > it should have a backing file of /var/lib/libvirt/images/host1.img. > Wonder why your 'qemu-img info' output didn't show that fact? I’m not sure. File is definitely there but hasn’t been used since creation it seems. Something else I don’t quite understand. # ls -l /var/lib/libvirt/images/host1.img -rw------- 1 qemu qemu 25769803776 Jan 19 16:58 /var/lib/libvirt/images/host1.img I presume that had I never created a snapshot then its this file that would change as the VM is used? >>> >>> I don't quite have a full picture of how you got into the situation. If >>> you are trying to just get rid of the snapshot, you could always try >>> 'virsh snapshot-delete --metadata host1 snap1-host1', to make libvirt >>> forget about the snapshot without cleaning up any actual data (leaving >>> any external backing chains intact, and not removing internal snapshots >>> from qcow2 files). >> >> ok. What implications does this have long term? >> Is there then a related step to remove the data of the snapshot that is no longer referenced? >> Reclaiming the space would be handy. > > Are you trying to revert to that state, or just forget that you ever > took the snapshot? Are you okay keeping the two files as a backing > chain, or do you want to collapse it into one? And if you DO want to > collapse into one file (so you can delete the other), do you want the > kept file to be snap1-host1.qcow2 (do a blockpull operation) or > host1.img (do a commit operation)? ok. What I’d like is to have a state where the snapshot I took never existed. Which I assume means that the img file in /var/lib/libvirt/images becomes the file used as the VM as its used? Then I’d like to make a snapshot of the guest - memory and disk state. But the second disk be excluded (its a separate mount point for the guest for MySQL data) But if I can get it working reliably a snapshot of both disks would also be desirable for me. >> And as before, given the structure of the VM and its two disks, how is a snapshot created >> excluding the second disk? vdb in the above xml output? > > If you create the snapshot via command line, 'virsh snapshot-create-as > host1 --name ... --diskspec vda,file=/path/for/disk --diskspec > vdb,snapshot=no' should be sufficient to exclude vdb from the snapshot > (you can use the --print-xml option to see what those options would > actually pass to the virDomainSnapshotCreateXML command). ok. in “/path/for/disk” is that a path or a filename - called “disk” and can it be anything? The default seem sot have been /var/lib/libvirt/ Is that not ideal?? Thanks again. This is helping. regards rolf. >> >> Many thanks for your help so far. > > Glad to hear it, and hope we can continue to be helpful. > > -- > Eric Blake eblake redhat com +1-919-301-3266 > Libvirt virtualization library http://libvirt.org > _______________________________________________ libvirt-users mailing list libvirt-users@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvirt-users
