Use one of the following methods to stop and start 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 the instance, run the following command: $ nova unpause INSTANCE_NAME

Administrative users might want to suspend an instance if it is infrequently used or to perform system maintenance. When you suspend an instance, its VM state is stored on disk, all memory is written to disk, and the virtual machine is stopped. Suspending an instance is similar to placing a device in hibernation; memory and vCPUs become available to create other instances. 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

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 complete 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. Use the following command: $ nova shelve SERVERNAME 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 that instance off the hypervisor in order to minimize resource usage: $ nova shelve-offload SERVERNAME