Upgrade RHE 7.6 to 8 on a LVM system

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I want to upgrade to Red Hat 8 but in the documentation:
https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html-single/upgrading_to_rhel_8/index#known-issues-upgrading-to-rhel-8

Among the Known limitations it says;
"No disk, LVM, or file-system encryption can currently be used on a system targeted for an in-place upgrade."

My system is LVM, how can I upgrade it?

Responses

I read that as the encryption being the problem, and I have also updated a test server (with a couple of minor issues) which did have an LVM root partition so I think you should be okay, though I recommend you have a good plan to get back to where you started from if the update doesn't work as expected.

I'd highly recommend against an upgrade from 7.x to 8.x. Minor release upgrades (number to the right of the period) are fine. I recognize Red Hat made a path to do a major upgrade, but even if it wasn't LVM and even if it will work with LVM, I'd severely recommend against an upgrade to another major release. There are numerous other posts regarding warnings against this. I know of one person who said they were able to do an upgrade from 7.x to 8.x.

If you really feel compelled to do that upgrade - make sure to do the following first.
1) Plan on upgrading from 7.x to 8.x as a high-risk task that will easily fail. Fully assess what roles the server you are going to put at risk so you know what roles it performs

2) Taking the information from #1 above, make a plan to back up the critical data from each role the server fulfills. Do not shortcut the time necessary to do this. Act like you are preparing for what you're going to do in order to build your server from scratch and you're going to want to have a full backup of any critical data to restore function to your server.

3) Take the necessary time to outline in time, effort, resources all the steps you've discovered in step 2. Have a plan for each role the server fulfills. Show it to some seasoned administrators who will not just say "yeah try it". If this is a critical server that your business relies on, be ready to acquire the time of the skilled admins to fulfill the plans you made in step #2 above.

4) Take the time for the admins to fulfill the tasks you discovered in step #3 above. Do not rush this. Allow all the time necessary. During this time, you may discover you require additional hardware, maybe a raid array, or something else, or maybe if your server you're upgrading is a server and you're going to have to make sure the data can go into another server after a total rebuild. Do not do this until you have thought this through on paper, or in some rational document.

5) After making sure you've backed up and staged a system to load from scatch, ensure you have everything necessary to load the system from scratch and to be able to restore function for every role it fulfills.

6) After you have fully prepared for the worst (the upgrade from 7.x to 8.x to fail) and you are fully convinced you have prepared to reload the system from scratch and you have the ability to restore function, then and only then proceed with the high-risk upgrade from 7.x to 8.x. Important: Schedule this at a time where you can buckle down and perform not only this, but if it goes badly, you can have the time necessary to execute your plan B you ran through in the steps prior to this. NOTE: Red Hat did not support an in-place upgrade from 6.x to 7.x, even though there is a procedure to attempt it, It would be good for you to know if they support an in-place upgrade from 7.x to 8.x prior to proceeding

7) Thoroughly evaluate the high-risk upgrade after you performed it to ensure the server actually fulfills all of it's roles. Evaluate it after reboots. Test every function thoroughly.

8) Let this go for at least a few days of testing. If it fails or did not go well, implement your plan B you went through in preparing for this in the steps above.

I hope that your upgrade from 7.x to 8.x goes well. I would never recommend anyone perform it. Hopefully I'm wrong in your case.

Regards,

RJ

One addition: if you have enough free disk space in LVM (or if you can add it) to make an LVM snapshot of the entire root file system, you can install the 'boot manager' package / utility in RHEL 7.6, then use it to make a "roll-back" boot entry in the GRUB boot menu that will take you back to the pre-upgrade kernel and pre-upgrade root file system. This could be a potential life-saver for risky in-place upgrades. Search for "boom" in the RHEL 7.6 Release Notes & documentation for complete details on how to install & use it.

(I tested it during the RHEL 8 beta process, and saw it demo'ed for a RHEL 7.6->8.0 upgrade; pretty handy little bit of software)

Hi Daniele,

I couldn't agree more with what RJ told you. My "two cents" : DON'T DO THAT ... do not even try to upgrade from 7 to 8 !
My sincere recommendation : Backup your data and perform a clean (fresh) installation of RHEL 8 - you won't regret it. :)

Regards,
Christian