Boot from rescue image¶

Sometimes you need to boot your instance from a ISO image to fix things that are not possible to fix when the filesystem on the boot volume volume is mounted. A rescue image can be used in these scenarios to boot an alternate operating system which can in turn fix the problem(s) with the volume.

While there is a function in the Cloud management portal, it only supports mounting a rescue image on instances that are not booting from a volume (which will be the most common scenario). We will therefore focus on using the OpenStack Terminal Client below.

OpenStack Terminal Client¶

To boot your instance from a rescue image using the OpenStack Terminal Client, follow these steps:

• We provide a public SystemRescue image that can be used.

• You can use a custom rescue image or use our guide here to create one.

• To connect the image to the instance, run this command $ openstack --os-compute-api-version 2.87 server rescue --image <ISO_NAME> <INSTANCE_NAME>, replacing the <ISO_NAME> with the name from previous step and the <INSTANCE_NAME> with the name of the instance that should mount the image. It takes a few minutes for server to go through a series of states and finally start. Manage server via console.

• When done, un-mount the image by running this command: $ openstack server unrescue <INSTANCE_NAME>.