ISU from Centos to Rocky 8

We are planning to upgrade from Centos 7.9 to Rocky 8.
We have system in production, and I need to understand if we can upgrade the production as ISU (in service upgrade) or do we need to stop the applications, use the script to upgrade the operating system and restart the application.

Hi @ssasporta , There is no upgrade path from any version of 7 to Rocky 8, and similarly, from any version of 8 to 9. Major versions require a reinstallation of the OS. I should say that “there is no supported way” of doing this. If you had a version of Centos 8.x, then you could upgrade to Rocky Linux 8 using the script.

Yes, you right. The whole plan is to first step upgrade to Centos 8 and second step to upgrade to Rocky 8.
Which means that in production we will have to do the same.
Can we do it ISU?

I’d call that “sidegrade” as it converts one el8 into another el8. That is a script and a reboot is required.

Alas, there is no CentOS Linux 8 any more. Even if there were, there never was supported in-place conversion from one CentOS major version into another major version. (E.g. from 7 to 8.)

The main point is that RHEL 7, RHEL 8, and RHEL 9 (and hence CentOS Linux 7 and Rocky Linux [89]) are three distinct Linux distros. There is no ISU. There is no supported “conversion script” either. (Well, Red Hat has something for RHEL and AlmaLinux offers ELevate but neither script can convert all systems.)

Install new system “from scratch”. Configure it appropriately. Transfer the “user data” (of the application). Finally, switch the clients to use the new server.

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Thanks for the information.