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<p class="MsoNormal">Hi,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">We are considering the following use-case of libvirt’s domain snapshot (and revert) feature:<o:p></o:p></p>
<ol style="margin-top:0cm" start="1" type="1">
<li class="MsoListParagraph" style="margin-left:0cm;mso-list:l1 level1 lfo1">Domain is qemu<o:p></o:p></li><li class="MsoListParagraph" style="margin-left:0cm;mso-list:l1 level1 lfo1">Snapshot type is disk-only (VIR_DOMAIN_SNAPSHOT_CREATE_DISK_ONLY)<o:p></o:p></li><li class="MsoListParagraph" style="margin-left:0cm;mso-list:l1 level1 lfo1">Snapshot location is internal (VIR_DOMAIN_SNAPSHOT_LOCATION_INTERNAL)<o:p></o:p></li><li class="MsoListParagraph" style="margin-left:0cm;mso-list:l1 level1 lfo1">All of the VM disks are:<o:p></o:p></li><ol style="margin-top:0cm" start="1" type="a">
<li class="MsoListParagraph" style="margin-left:0cm;mso-list:l1 level2 lfo1">Network type (VIR_STORAGE_TYPE_NETWORK)<o:p></o:p></li><li class="MsoListParagraph" style="margin-left:0cm;mso-list:l1 level2 lfo1">RBD protocol (VIR_STORAGE_NET_PROTOCOL_RBD)<o:p></o:p></li><li class="MsoListParagraph" style="margin-left:0cm;mso-list:l1 level2 lfo1">Raw format (VIR_STORAGE_FILE_RAW)<o:p></o:p></li></ol>
<li class="MsoListParagraph" style="margin-left:0cm;mso-list:l1 level1 lfo1">VM can be either active or inactive<o:p></o:p></li></ol>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">We want to extend libvirt to support this use-case.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Consider the following changes:<o:p></o:p></p>
<ol style="margin-top:0cm" start="1" type="1">
<li class="MsoListParagraph" style="margin-left:0cm;mso-list:l0 level1 lfo3">For the inactive VM case, libvirt currently calls “qemu-img snapshot” for taking a snapshot, as well as reverting (adding “-a” to qemu-img).<br>
The same would also work for our-use case, as basically the same qemu-img command would work for RBD disks as well (using rbd:poolname/imagename as the filename).<br>
So basically we need to reuse code from qemuDomainSnapshotForEachQcow2Raw.<o:p></o:p></li><li class="MsoListParagraph" style="margin-left:0cm;mso-list:l0 level1 lfo3">For the active VM case, we can re-use code from qemuDomainSnapshotCreateActiveExternal, but call qemu’s “snapshot_blkdev_internal” instead of the current “snapshot_blkdev”.<br>
This would work for RBD disks, but more generally for any qemu block driver which implements “bdrv_snapshot_create”.<o:p></o:p></li></ol>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">BTW it seems to me that if you try to take an internal snapshot of just the disks, you will actually get an external snapshot? Or is there some place in the code which validates and fails this case?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Anyhow, I would really appreciate any feedback or thoughts.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks,<o:p></o:p></p>
<p class="MsoNormal">Or<o:p></o:p></p>
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