Boot from rescue image

Sometimes you need to boot your instance from an ISO image because the mounted filesystem on the boot volume prevents you from fixing certain issues.

You can use a rescue image in these scenarios to boot an alternate operating system, which can then fix problems with the volume.

The Cloud management portal includes a rescue function, but it only lets you mount a rescue image on instances that don’t boot from a volume.

You need to use OpenStack Horizon or the OpenStack Terminal Client

We provide a public SystemRescue image that you can use.

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

Caution

This operation stops the instance, boots it from the rescue image, and makes it available only through the console

Tip

If you’ve created a custom rescue image remember to delete the image or you will pay an hourly fee per GB for the image, see our price list.

OpenStack Horizon

  • Under Project, click Compute and then Instances in the sidebar menu

  • Open the actions dropdown to the right of the instance you want to resize and click Rescue Instance

  • Select a rescue image and click Confirm

  • It will take a few minutes for the instance to start with the rescue image. Use the console to manage the instance when in rescue mode.

  • When you’re done with rescue click the actions dropdown again and click Unrescue Instance

OpenStack Terminal Client

  • Run the rescue action for the instance using the image UUID or image name

openstack --os-compute-api-version 2.87 server rescue --image <image> <instance>

  • It will take a few minutes for the instance to start with the rescue image. Use the console to manage the instance when in rescue mode.

  • When you’re done with rescue remove the rescue image from the instance

openstack server unrescue <instance>

See also