Reboot an Instance
Problem
User has the need to reboot an instance.
Environment
- Platform9 Managed OpenStack - All Versions
- Nova
Procedure
- By default, when an instance is rebooted, it is a soft reboot. A soft reboot attempts a graceful shutdown and restart of the instance.
- To perform a hard reboot, pass the
--hardparameter. A hard reboot power cycles the instance.
- Rescue mode provides a way for access, even if an image renders the instance inaccessible. By default, it starts an instance from the initial image attaching the current boot disk as a secondary one. For example, this operation may be performed, if a filesystem of an instance becomes corrupted due to prolonged use.
1. To perform an instance reboot into rescue mode, run the following command.
$ openstack server rescue SERVER2. To restart the instance from the normal boot disk, run the following command.
$ openstack server unrescue SERVER 3. If you want to rescue an instance with a specific image, rather than the default one, use the --image parameter.
$ nova rescue --image IMAGE_ID SERVERNote: On running the --openstack server rescuecommand, the 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 shutdown behavior is configured by the shutdown_timeoutparameter that can be set in the nova.conf file. Its value stands for the overall period (in seconds) a guest operating system is allowed to complete the shutdown. The default timeout is 60 seconds. The timeout value can be overridden on a per image basis by means of os_shutdown_timeoutthat is an image metadata setting allowing different types of operating systems to specify how much time they need to shut down cleanly.