Performing a Diagnostic Reboot

Use a diagnostic reboot to rebuild an unreachable compute virtual machine (VM) instance when other troubleshooting steps aren't successful.

During a diagnostic reboot, the instance is stopped, rebuilt, and restarted. A short downtime occurs during the reboot process. Instance properties such as private and ephemeral public IP addresses, attached block volumes, and virtual network interface cards (VNICs) are preserved.

Important

Before you send a diagnostic reboot, restart the instance's OS and confirm that the instance is configured correctly. See the Compute troubleshooting suggestions and Networking troubleshooting suggestions. Use diagnostic reboot as a final attempt to troubleshoot an unreachable 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.

For administrators: The policy in Let users launch compute instances includes the ability to perform a diagnostic reboot on an instance. If the specified group doesn't need to launch instances or attach volumes, you could simplify that policy to include only manage instance-family, and remove the statements involving volume-family and virtual-network-family.

If you're new to policies, see Getting Started with Policies and Common Policies. For reference material about writing policies for instances, cloud networks, or other Core Services API resources, see Details for the Core Services.

Prerequisites

  • Ensure that any block volumes defined in /etc/fstab use the recommended options.
  • Ensure that any File Storage service (NFS) mounts use the nofail option.
  • If you use the Oracle-provided script to configure secondary VNICs, ensure it runs automatically at startup.

Supported Shapes

All VM shapes except shapes in the dense I/O series support diagnostic reboots.

Using the Console

  1. Open the navigation menu and click Compute. Under Compute, click Instances.
  2. Click the instance that you're interested in.
  3. Click More Actions, and then click Send diagnostic reboot.
  4. Review the confirmation message and then click Send diagnostic reboot.

Using the API

Use the InstanceAction operation, passing the value DIAGNOSTICREBOOT as the action to perform.

Using the CLI

Open a command prompt and run the instance action command:

oci compute instance action --action DIAGNOSTICREBOOT --instance-id <INSTANCE_OCID>