Oracle Cloud Infrastructure Documentation

Replacing a Boot Volume

You can automatically replace the boot volume of an instance without terminating and recreating the instance. The instance stops, replaces the boot volume, and returns the instance to the state prior to the volume replacement process. This feature allows the replacement of boot volumes if an issue is detected or an upgrade is needed to implement new features.

Important

Boot volume replacement is only supported for virtual machine instances.

Boot Volume Replacement Requirements and Options

The following are the key OS and images requirements to use boot volume replacement:

  • Only Linux operating systems and images are supported.
  • Windows and marketplace images are not supported.
  • Boot volumes can only be replaced with block volumes and images that use the same Linux distribution. For example, you cannot switch from Oracle Linux to Ubuntu or vice versa.
  • Image limitations apply for launch options associated with the image and what is currently on the instance. If for example the boot volume attachment type of the image doesn't match the instance launch options then the image is considered invalid.

In regard to instances you must have:

  • A virtual machine instance.
  • And one of the following:
    • A formatted block volume with a compatible operating system.
    • A backup image that is compatible with your instance.

Required IAM Policy

To use Oracle Cloud Infrastructure, you must be granted security access in a policy  by an administrator. This access is required whether you're using the Console or the REST API with an SDK, CLI, or other tool. If you get a message that you don't have permission or are unauthorized, verify with your administrator what type of access you have and which compartment  to work in.

To enable boot volume replacement, add the required policies for your compartment or tenancy. The following are examples of administration level instance policies that allow boot volume replacement for a compartment and a tenancy.

Example Policies for a Compartment

allow group InstanceUpdaters to manage instances in compartment instanceCompartment
OR
allow group InstanceUpdaters to manage instance-family in compartment instanceCompartment

Example Policies for a Tenancy

allow group InstanceUpdaters to manage instances in TENANCY
OR
allow group InstanceUpdaters to manage instance-family in TENANCY

For an existing set of policies, the following policy is the minimum required change to allow boot volume replacement.

allow group InstanceUpdaters to {INSTANCE_BOOT_VOLUME_REPLACE} in instanceCompartment
Note

In the examples, InstanceUpdaters is a policy group that allows updates to instances.

Rollback for Boot Volume Replacement

If a problem is encountered performing a block volume replacement, the system attempts to rollback the instance to it's original state. The steps performed include:

  • Restore the instance metadata.
  • Restore the instance state.
  • Restore the attached volumes state.
  • Restart the instance.

Ideally, this restores the instance to its prior state. This might not be possible in all circumstances.

Note

When a rollback occurs, the new destination volume is handled as follows:
  • When an image is used, rollback deletes the generated boot volume.
  • When a volume OCID is used, rollback doesn't delete the destination boot volume.

Using the Console

Select the Boot Volume Options

To replace the boot volume for an instance, do the following.

  1. Open the navigation menu and click Compute. Under Compute, click Instances.
  2. Click the name of the instance.
  3. From the More Actions menu item, select Replace Boot Volume.
  4. Configure replace boot volume options:
    • Preserve Boot Volume: If Enabled, the previous boot volume is preserved after successful replacement. Otherwise, the boot volume is terminated.

Select a Replacement Boot Volume

Select your replacement volume using one of the following methods.

Replace with a Boot Volume using a List
  1. Under Replace by select Boot Volume.
  2. Under Apply boot volume by then select Select from list.
  3. Click the list to select the volume.
    Note

    You have the option to change the compartment.
Replace with a Boot Volume using an OCID
  1. Under Replace by select Boot Volume.
  2. Under Apply boot volume by then select Input OCID.
  3. Enter the OCID for the boot volume.
Replace with an Image using a List
  1. Under Replace by select Image.
  2. Under Apply image by then select Select from list.
  3. Click the list to select the image.
    Note

    You have the option to change the compartment.
Replace with an Image using an OCID
  1. Under Replace by select Image.
  2. Under Apply image by then select Input OCID.
  3. Enter the OCID for the image.

Confirm your Choice

Click Replace to make your selection.

Using the CLI

Use the update instance command and required parameters to update an instance:

oci compute instance update --from-json <file://path/to/file.json>

<file://path/to/file.json> is the path to a JSON file that defines the instance details. For information about how to generate an example of the JSON file, see Advanced JSON Options.

For a complete list of flags and variable options for the Compute Service CLI commands, see the command line reference for Compute.