Rebooting an Instance

You can perform a soft or hard reboot on a running instance. A soft reboot attempts a graceful shut down and restart of the instance. A hard reboot power cycles the instance.

By default, the server reboot command performs a soft reboot on the instance.

$ openstack server reboot <INSTANCE>

To perform a hard reboot:

$ openstack server reboot --hard <INSTANCE>

It is also possible to reboot a running instance into rescue mode. For example, this operation may be required if a filesystem of an instance becomes corrupted with prolonged use.

Note:

  • Rescue is not supported for volume-backed instances.
  • Suspend and stop operations are not allowed when an instance is running in rescue mode. Triggering these actions causes the loss of the original instance state and makes it impossible to unrescue the instance.

Rescue mode provides a mechanism for access, even if an image renders the instance inaccessible. By default, the rescue command starts an instance from the initial image, attaching the current boot disk as a secondary one.

To perform an instance reboot into rescue mode:

$ openstack server rescue <INSTANCE>

Note:
On running the rescue command, an instance performs a soft shutdown first. This means that the guest operating system has a chance to perform a controlled shutdown before the instance is powered off. The default timeout is 60 seconds. 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.

To restart the instance from the normal boot disk:

$ openstack server unrescue <INSTANCE>