Thoughts on migration/upgrade of older systems?
 

We've got a few older systems at our office which are in need of some updates.

The machines in question are Redhat 8 and 9 boxes which are currently used for (external) mail, (external) web, and (internal, development arena) home directories.

The mail and web configurations have been customized, so we will have to look at carrying that data to a new host. The home directories are served from a fairly "vanilla" configuration; I believe the data will simply need to be migrated to the new host and automount maps updated to reflect the new host.

New installations on freshened hardware are reasonable, we are not thinking of upgrading but rather re-implementing or re-deploying.


Rambling aside, I'm looking for feedback in the following areas:

- user migration from the old mail host to the new. How can this be achieved? Copy the relevant lines from passwd and shadow as well as current imap files in spool and home directories?

- home directory data migration - Place the new server on the network and rsync the data from one host to another, using that to maintain ownership and permissions?

- Any thoughts on an easy way to find other pieces of the system which may have been modified in the last few years while the boxes were running? While we have log books for the servers, a cli sequence might point out things which were updated and not logged.


Thanks for any feedback or pointers you can provide!

Why don't you just perform a backup on the old system and restore on the new? Of course there are a couple of additional steps such as installing a boot loader in the MBR of the new disk but I would give it a try.

Backup and restore - so keep the same old OS load? That keeps us exposed to the same old shortcomings of using an EOL software product.

Looks like I'll be using rpm to check for changed files, manually investigate changes, and carry those changes which are *important* to the new system. I'll also be looking at the server log books for information on things that have changed since the system was built.



Other thoughts?

I don't think that stress_junkie meant to restore the OS. But mail, homedirectories etc can be done like that.
Just check for each software that you use for the upgrades; there are usually guidelines available how to migrate specific software.

One example that I can think of is MySQL where somewhere along the line the password function changed and needed more storage space. If this applies, you have to check all databases for the use of the password function and the allocated storage space.

Good point, and better meaning than I took from it. I'll take my list of files installed by rpms that have been modified and pursue my upgrade/redeployment options on those.


At this point, the database servers are not impacted by this upgrade, although there are some hosted applications which speak to them. I'll have to see what we can learn about updating the connections.

Manually rsyncing is a fine choice, and would probably prove to be much more effective than anything else.

Your biggest problem may come from the fact that RH8 and RH9 are fairly ancient at this time, and you might gain/lose functionalities in an upgrade to modern OSes. As an example, all the home directory data will probably copy beautifully, but the apache running on those boxes is a very old version, and your side apps may not exist or have important changes that poke holes in your current setup.

Take your time, and try running the replacement system side by side for a while, just to make sure everything behaves itself exactly as it should before you scrap the old ones.

Peace,
JimBass