Migrating from AlmaLinux 8 to AlmaLinux 9

This article contains instructions for updating the operating system (OS) on the platform server and cluster nodes from AlmaLinux 8 to AlmaLinux 9.

If you need to change the OS from AlmaLinux 8 to AlmaLinux 10, follow the instructions in this article, and then update the OS according to the article Migrating from AlmaLinux 9 to AlmaLinux 10.

Update procedure

Platform server

To update the OS:

Check the compatibility of the hardware with new AlmaLinux version. To do this, boot the AlmaLinux OS in Live Media mode.
Create a backup of the platform on external storage. For more information, see Creating platform backups.
Follow the instructions in the OS Update section.

The platform will be unavailable during the OS change process.

Cluster node

There are two options for updating the OS:

with virtual machines (VMs) migrated to another node — the recommended method;
without transferring VMs — successful update is not guaranteed, use this method at your own risk.

To update the OS with VMs migration:

Migrate VMs to another node. For more information, see Migration of virtual machines.
Delete the cluster node.
Erase server disks and install new AlmaLinux version on it.
Connect the node to the cluster.
MIgrate VMs back to the node.

To update the OS without VMs migration:

Check the compatibility of the hardware with new AlmaLinux version. To do this, boot the AlmaLinux OS in Live Media mode.
Follow the instructions in the OS Update section.
VMs on the cluster node will be unavailable during the OS change process.

OS update

Connect to the server via SSH. For more information about connecting via SSH, see Workstation setup.
Update the software:
```
yum update
```
Reboot the server:
```
reboot
```
Connect to the server via SSH again.

Install the ELevate software:

yum install -y http://repo.almalinux.org/elevate/elevate-release-latest-el$(rpm --eval %rhel).noarch.rpm

Instal the Leapp framework:

yum install -y leapp-upgrade leapp-data-almalinux

Configure the Leapp framework:

leapp answer --section check_vdo.confirm=True

Check if the system is ready for the OS change:
```
leapp preupgrade
```
Examine the output of the command and the report file /var/log/leapp/leapp-report.txt. They contain information about possible problems when changing OS.
Start the OS change:
```
leapp upgrade
```
Reboot the server:
```
reboot
```
- The server may reboot longer than usual due to the OS change.
- Ensure that the AlmaLinux 9 kernel is selected in the boot loader menu.
Connect to the server via SSH again.
Check the OS version:
```
cat /etc/os-release
```
Remove the Leapp temporary directory:
```
rm /root/tmp_leapp_py3 -fr
```
Remove the AlmaLinux 8 packages:
1. Get the package list:
```
rpm -qa | grep el8
```
2. Remove each package from the list with the command:
```
dnf remove <package_name>
```

If the frr service was used on the cluster node

Connect to the cluster node via SSH. For more information about connecting via SSH, see Workstation setup.
In the file /etc/yum.repos.d/frr-stable.repo, replace links of the form
```
https://rpm.frrouting.org/repo/el8
```
to
```
https://rpm.frrouting.org/repo/el9
```
Update the software:
```
dnf update
```