第14章 Upgrading the Compute node operating system
You can upgrade the operating system on all of your Compute nodes to RHEL 9.2, or upgrade some Compute nodes while the rest remain on RHEL 8.4.
If your deployment includes hyperconverged infrastructure (HCI) nodes, you must upgrade all HCI nodes to RHEL 9. For more information about upgrading to RHEL 9, see Upgrading Compute nodes to RHEL 9.2.
For information about the duration and impact of this upgrade procedure, see Upgrade duration and impact.
Prerequisites
If you are using Red Hat Ceph Storage, before performing the Leapp upgrade verify if the ceph-common package is present on your Compute nodes. If the ceph-common package is present on a node, take the precautions described in Upgrading RHCS 5 hosts from RHEL 8 to RHEL 9 removes ceph-common package. Services fail to start. to ensure the Red Hat Ceph Storage services restart after the Compute node reboots after the Leapp upgrade.
14.1. Selecting Compute nodes for upgrade testing
The overcloud upgrade process allows you to either:
- Upgrade all nodes in a role.
- Upgrade individual nodes separately.
To ensure a smooth overcloud upgrade process, it is useful to test the upgrade on a few individual Compute nodes in your environment before upgrading all Compute nodes. This ensures no major issues occur during the upgrade while maintaining minimal downtime to your workloads.
Use the following recommendations to help choose test nodes for the upgrade:
- Select two or three Compute nodes for upgrade testing.
- Select nodes without any critical instances running.
If necessary, migrate critical instances from the selected test Compute nodes to other Compute nodes. Review which migration scenarios are supported:
Expand Source Compute node RHEL version Destination Compute node RHEL version Supported/Not supported RHEL 8
RHEL 8
Supported
RHEL 8
RHEL 9
Supported
RHEL 9
RHEL 9
Supported
RHEL 9
RHEL 8
Not supported
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