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14.15.2. Managing Snapshots

The sections that follow describe actions that can be done in order to manipulate domain snapshots. Snapshots take the disk, memory, and device state of a domain at a specified point-in-time, and save it for future use. Snapshots have many uses, from saving a "clean" copy of an OS image to saving a domain’s state before what may be a potentially destructive operation. Snapshots are identified with a unique name. See the libvirt website for documentation of the XML format used to represent properties of snapshots.

14.15.2.1. Creating Snapshots

The virsh snapshot-create command creates a snapshot for domain with the properties specified in the domain XML file (such as <name> and <description> elements, as well as <disks>).
To create a snapshot, run:
# snapshot-create <domain> <xmlfile> [--redefine] [--current] [--no-metadata] [--reuse-external] 
The domain name, ID, or UID may be used as the domain requirement. The XML requirement is a string must contain the <name>, <description> and <disks> elements.

Note

Live snapshots are not supported in Red Hat Enterprise Linux. There are additional options available with the virsh snapshot-create command for use with live snapshots which are visible in libvirt, but not supported in Red Hat Enterprise Linux 6.
The options available in Red Hat Enterprise Linux include:
  • --redefine specifies that if all XML elements produced by snapshot-dumpxml are valid; it can be used to migrate snapshot hierarchy from one machine to another, to recreate hierarchy for the case of a transient domain that goes away and is later recreated with the same name and UUID, or to make slight alterations in the snapshot metadata (such as host-specific aspects of the domain XML embedded in the snapshot). When this option is supplied, the xmlfile argument is mandatory, and the domain’s current snapshot will not be altered unless the --current option is also given.
  • --no-metadata creates the snapshot, but any metadata is immediately discarded (that is, libvirt does not treat the snapshot as current, and cannot revert to the snapshot unless --redefine is later used to teach libvirt about the metadata again).
  • --reuse-external, if used, this option specifies the location of an existing external XML snapshot to use. If an existing external snapshot does not already exist, the command will fail to take a snapshot to avoid losing contents of the existing files.