20.7. Managing a Virtual Machine Configuration

The virsh save [--bypass-cache] domain file [--xml string] [--running] [--paused] [--verbose] command stops the specified domain, saving the current state of the guest virtual machine's system memory to a specified file. This may take a considerable amount of time, depending on the amount of memory in use by the guest virtual machine. You can restore the state of the guest virtual machine with the virsh restore (Section 20.6.4, “Restoring a Guest Virtual Machine”) command.

The difference between the virsh save command and the virsh suspend command, is that the virsh suspend stops the domain CPUs, but leaves the domain's qemu process running and its memory image resident in the host system. This memory image will be lost if the host system is rebooted.

The virsh save command stores the state of the domain on the hard disk of the host system and terminates the qemu process. This enables restarting the domain from the saved state.

You can monitor the process of virsh save with the virsh domjobinfo command and cancel it with the virsh domjobabort command.

The virsh save command can take the following arguments:

virsh save guest1 guest1-config.xml --running

# virsh save guest1 guest1-config.xml --running

The virsh define filename command defines a guest virtual machine from an XML file. The guest virtual machine definition in this case is registered but not started. If the guest virtual machine is already running, the changes the changes will take effect once the domain is shut down and started again.

virsh define guest1-config.xml

# virsh define guest1-config.xml

The virsh save-image-define filename [--xml /path/to/file] [--running] [--paused] command updates the guest virtual machine's XML file that will be used when the virtual machine is restored used during the virsh restore command. The --xml argument must be an XML file name containing the alternative XML elements for the guest virtual machine's XML. For example, it can be used to account for the file naming differences resulting from creating disk snapshots of underlying storage after the guest was saved. The save image records if the guest virtual machine should be restored to a running or paused state. Using the arguments --running or --paused dictates the state that is to be used.

virsh save-image-define guest1-config.xml --running

# virsh save-image-define guest1-config.xml --running

The virsh save-image-dumpxml file --security-info command will extract the guest virtual machine XML file that was in effect at the time the saved state file (used in the virsh save command) was referenced. Using the --security-info argument includes security sensitive information in the file.

virsh save-image-dumpxml guest1-config.xml

# virsh save-image-dumpxml guest1-config.xml

The virsh save-image-edit <file> [--running] [--paused] command edits the XML configuration file that was created by the virsh save command. See Section 20.7.1, “Saving a Guest Virtual Machine's Configuration” for information on the virsh save command.

When the guest virtual machine is saved, the resulting image file will indicate if the virtual machine should be restored to a --running or --paused state. Without using these arguments in the save-image-edit command, the state is determined by the image file itself. By selecting --running (to select the running state) or --paused (to select the paused state) you can overwrite the state that virsh restore should use.

virsh save-image-edit guest1-config.xml --running

# virsh save-image-edit guest1-config.xml --running