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49 lines
1.7 KiB
ReStructuredText
49 lines
1.7 KiB
ReStructuredText
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=========
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Snapshots
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=========
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.. contents::
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Manual storage snapshotting
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===========================
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Certain use cases such as block storage on LVM or disks backed via storage
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exported through the ``vhost-user-blk`` protocol may require that snapshots are
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done in conjunction with the storage provider which is not managed by **libvirt**.
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To achieve this such disks can use ``snapshot`` mode ``manual``. When a snapshot
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has a disk in manual mode the following happens:
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#. ``libvirt`` takes snapshot of the VM memory if requested
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#. If a live snapshot is requested (``VIR_DOMAIN_SNAPSHOT_CREATE_LIVE``) the
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VM runs until the memory snapshot phase completes and is then paused.
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#. Otherwise the VM is paused right away.
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#. Snapshot of disks which are marked for external snapsot is executed
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#. The API return success, the VM is paused.
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#. The user snapshots the externally managed storage
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#. The user resumes the execution of the VM (``virsh resume $VM``)
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Overview of manual snapshots
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----------------------------
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Manual snapshot of a disk is requested by setting the ``snapshot`` property to
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``manual`` in the snapshot XML ::
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<domainsnapshot>
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<memory file='/path/to/memory/img'/>
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<disks>
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<disk name='vda' snapshot='manual'/>
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<disk name='vdb' snapshot='external'/>
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<disk name='vdc' snapshot='no'/>
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</disks>
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</domainsnapshot>
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or ``--diskspec vda,snapshot=manual`` when using ``virsh snapshot-create-as``::
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$ virsh snapshot-create-as --diskspec vda,snapshot=manual \
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--diskspec vdb,snapshot=external \
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--diskspec vdc,snapshot=no $VM \
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--memspec file=/path/to/memory/img
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