This is probably a super green question, but the person that set up my server originally has absconded, and I can't get a hold of him. Minor maintenance I can handle, but reconfiguration stuff like this freaks me out, and I'm unsure how to progress.
My wordpress install tells me this on the site health screen:
"For optimal performance and security reasons, we recommend running MariaDB version 10.0 or higher. Contact your web hosting company to correct this."
OK, fine. I went to see what version I was running, and the command line says this:
"mysql Ver 15.1 Distrib 5.5.68-MariaDB, for Linux (x86_64) using readline 5.1"
My question is this - how do I upgrade mysql while not blowing up everything - as I have like nearly a dozen domains that require use of MySQL, and if I start jacking with this (as I'm a relative neophyte here), I can't blow up everything. I leave it alone because everything works.
I'm running CentOS 7 on my Linode.
This may not be a simple copy paste solution here, but this guide should explain the steps involved. It may take a little research to find the exact MySQL version you'd like for the upgrade, and if you don't know your root password to perform the backups, you might be out of luck here.
Oh, I know the root pw, I log in routinely with it to do yum upgrades and other basic maintenance.
If that guy were still around, I could easily ask him, and it'd be nothing for him, but for me it's a big pile of scary stuff that can blow up nearly everything on all my domains.
Take a backup first, if you have backups enabled. You can take a manual backup of your Linode before you start, that way, if something does go wrong, you can restore from the backup and no harm should be done, then you can try again. If you have difficulty with the steps in your attempts, I'm sure there's someone here that knows a lot more about CentOS than I would, who might be able to help you. You can post everything you've tried and what the results were, that way, someone assisting can know where to look.
Unfortunately, I can't do that. The guy who set up my server set it up in such a way that Linode's internal backup option is unavailable to me.
I wish it wasn't the case, but I don't know enough to break it all down and rebuild it from the ground up.
Given your situation, if I were you, I would put the mysql version upgrade issue on hold for now and focus instead on the more important issue of "How do I backup my database and test that I can restore it if I need to?"
Don't worry about the Linode system level backups -- just focus on a database backup.
Try using either mysqldump or just the features of any good graphical database client (like TablePlus or DataGrip) to save a full back up. It should be possible to do this using a readonly database user so you don't have to worry about messing something up.
Once you have that backup, restore it into a fresh mysql installation unrelated to your main mysql, on a new temporary Linode, and view it through your database client, rifling through tables to gain confidence that it "looks right"
There is more to do after that if you want to test that you can restore the backup into the production server, but that is a good first step just to make sure you have it. I would not do any version upgrades or any other monkeying around until you are sure you have good backups.