openstack-manuals/doc/user-guide/source/cli_stop_and_start_an_instance.rst

Stop and start an instance

Use one of the following methods to stop and start an instance.

Pause and unpause an instance

To pause an instance, run the following command:

$ nova pause INSTANCE_NAME

This command stores the state of the VM in RAM. A paused instance continues to run in a frozen state.

To unpause an instance, run the following command:

$ nova unpause INSTANCE_NAME

Suspend and resume an instance

To initiate a hypervisor-level suspend operation, run the following command:

$ nova suspend INSTANCE_NAME

To resume a suspended instance, run the following command:

$ nova resume INSTANCE_NAME

Shelve and unshelve an instance

Shelving is useful if you have an instance that you are not using, but would like retain in your list of servers. For example, you can stop an instance at the end of a work week, and resume work again at the start of the next week. All associated data and resources are kept; however, anything still in memory is not retained. If a shelved instance is no longer needed, it can also be entirely removed.

You can run the following shelving tasks:

• Shelve an instance - Shuts down the instance, and stores it together with associated data and resources (a snapshot is taken if not volume backed). Anything in memory is lost.

$ nova shelve SERVERNAME

Note

By default, the nova shelve command gives the guest operating system a chance to perform a controlled shutdown before the instance is powered off. The shutdown behavior is configured by the shutdown_timeout parameter that can be set in the nova.conf file. Its value stands for the overall period (in seconds) a guest operation system is allowed to complete the shutdown. The default timeout is 60 seconds. See Description of Compute configuration options for details.

The timeout value can be overridden on a per image basis by means of os_shutdown_timeout that is an image metadata setting allowing different types of operating systems to specify how much time they need to shut down cleanly.

• Unshelve an instance - Restores the instance.

$ nova unshelve SERVERNAME

• Remove a shelved instance - Removes the instance from the server; data and resource associations are deleted. If an instance is no longer needed, you can move the instance off the hypervisor in order to minimize resource usage.

$ nova shelve-offload SERVERNAME