Atomicorp

Has anyone Migrated a Plesk installation from a server running MySQL 5.5 to one running 5.1?
I'd like to do so but I figure there's a possibility of problems. What I can't figure out is WHAT sort of problems.

Does Plesk do anything non-reversible on a 5.5 installation that a Migration wouldn't take care of -- at least that anybody knows of?

Sure, we could install 5.5 but I'm trying to keep this system Centos-6-stock so that I don't hit a third-party repo EOL issue.

Do you want to replace the MySQL installation on one machine from 5.5 to 5.1 *or* do you mean that you will migrate from machine A with MySQL 5.5 to machine B with MySQL 5.1?

Plesk will work fine with a migration between two servers with different MySQL versions, but that does not exclude that certain applications/websites still rely on 5.5. Also, some default settings have changed between 5.1 and 5.5. That said, if absolute reliance on 5.5 is not an issue you will probably do fine with a migration.

Even an in-place downgrade on the same machine is possible (we've done it before) but that entails some magic (dumping SQL, removing alternative packages, re-installing stock packages, ensuring configuration is alright, re-importing data, running MySQL upgrade script, etc.) which needs to be done very carefully and requires some downtime of services.

The second one -- Migrate (Using Plesk Migration Manager) from a machine running 5.5 to a different one running 5.1.

So, on the face of it, it looks doable as long as someone has not used a 5.5-specific feature. And I would say nobody has done so, so I'll hope it works OK

Thanks. I'll report back if it doesn't work

I think that should be OK, I know the data formats for grant tables are very different between them. So a typical mysql backup would probably not work, but assuming that the abstraction layer in the migration manager is there, it should shift between the different formats in the two.