Re: [libvirt] [PATCH] Added snapshot backing store parameters to virsh.

Hi all, This patch adds support for creation of snapshot volumes to the virsh "vol-create-as" command, which is presently missing it. Thinking it will be useful, as it's tricky to explain snapshots + hacking XML when writing up docs. Explaining things as parameters on a command line (no XML required) is so much easier. :) The snapshot support was added through two optional parameters to vol-create-as: --snapshot-source-vol backing_volume --snapshot-source-format volume_format The "--snapshot-source-vol" parameter is the name of a volume to use as the snapshot backing store. It has to be in the same storage pool as the volume being created. The "--snapshot-source-format" parameter is only needed for file based backing stores (ie qcow, qcow2, etc), and specifies the format of the backing store volume. In an ideal scenario, the --snapshot-source-format parameter would not be necessary, but there didn't appear to be a way to query the format of an existing volume to determine it automatically. (ie something like a virStorageVolGetFormat()) Example of using the new parameters with an LVM storage pool: ******************************************************** virsh # vol-list guest_images_lvm Name Path ----------------------------------------- rhel6vm1lun1 /dev/guest_images_lvm/rhel6vm1lun1 testvol /dev/guest_images_lvm/testvol virsh # vol-create-as guest_images_lvm snapvol1 5G --snapshot-source-vol rhel6vm1lun1 Vol snapvol1 created virsh # vol-create-as guest_images_lvm snapvol2 5G --snapshot-source-vol rhel6vm1lun1 Vol snapvol2 created virsh # vol-create-as guest_images_lvm snapvol3 5G --snapshot-source-vol rhel6vm1lun1 Vol snapvol3 created virsh # vol-list guest_images_lvm Name Path ----------------------------------------- rhel6vm1lun1 /dev/guest_images_lvm/rhel6vm1lun1 snapvol1 /dev/guest_images_lvm/snapvol1 snapvol2 /dev/guest_images_lvm/snapvol2 snapvol3 /dev/guest_images_lvm/snapvol3 testvol /dev/guest_images_lvm/testvol # virsh # quit # lvs guest_images_lvm LV VG Attr LSize Origin Snap% Move Log Copy% Convert rhel6vm1lun1 guest_images_lvm owi-a- 20.00g snapvol1 guest_images_lvm swi-a- 5.00g rhel6vm1lun1 0.00 snapvol2 guest_images_lvm swi-a- 5.00g rhel6vm1lun1 0.00 snapvol3 guest_images_lvm swi-a- 5.00g rhel6vm1lun1 0.00 testvol guest_images_lvm -wi-a- 20.00g # ******************************************************** Example of using the new parameters with a directory storage pool: ******************************************************** virsh # vol-list image_dir Name Path ----------------------------------------- imagevol1.qcow2 /home/images/imagevol1.qcow2 virsh # vol-create-as image_dir qcow2snap1 5G --format qcow2 --snapshot-source-vol imagevol1.qcow2 --snapshot-source-format qcow2 Vol qcow2snap1 created virsh # vol-create-as image_dir qcow2snap2 5G --format qcow2 --snapshot-source-vol imagevol1.qcow2 --snapshot-source-format qcow2 Vol qcow2snap2 created virsh # vol-create-as image_dir qcow2snap3 5G --format qcow2 --snapshot-source-vol imagevol1.qcow2 --snapshot-source-format qcow2 Vol qcow2snap3 created virsh # vol-list image_dir Name Path ----------------------------------------- imagevol1.qcow2 /home/images/imagevol1.qcow2 qcow2snap1 /home/images/qcow2snap1 qcow2snap2 /home/images/qcow2snap2 qcow2snap3 /home/images/qcow2snap3 virsh # quit # ls -la /home/images/ total 552 drwx------. 2 root root 4096 Jun 5 22:10 . drwxr-xr-x. 7 root root 4096 Jun 5 16:51 .. -rw-------. 1 root root 262144 Jun 5 16:53 imagevol1.qcow2 -rw-------. 1 root root 262144 Jun 5 22:10 qcow2snap1 -rw-------. 1 root root 262144 Jun 5 22:10 qcow2snap2 -rw-------. 1 root root 262144 Jun 5 22:10 qcow2snap3 # ******************************************************** A Red Hat BZ has been created for tracking this, if useful: https://bugzilla.redhat.com/show_bug.cgi?id=600652 Regards and best wishes, Justin Clift On 06/05/2010 10:13 PM, Justin Clift wrote: <snip> -- Salasaga - Open Source eLearning IDE http://www.salasaga.org