42% of U7 hosts, which are on the new cluster, got their MySQL migrated onto SSDs now! 🎉 will probably be done today.
Some explanation on what we're even up to. The process for this is fairly straight forward:
1. mount SSD storage
2. rsync w/ MariaDB running
3. stop MariaDB
4. rsync w/o MariaDB running
5. move /var/lib/mysql away
6. bind-mount SSD storage to there
7. start MariaDB
If we're lucky and no data changes between 2. and 3., step 4 is pretty much instant. That means almost no downtime. If we're unlucky, a bunch of stuff changed which leads to >20 minutes of downtime :(
Admittedly, you can build the whole thing way more efficient and without any downtime using a primary/secondary setup. But any run-time we would have saved doing that, we'd have probably lost in dev-time. The latter one is more limited right now, so here we are.
Admittedly-admittedly it's not very smart to have MySQL on the application hosts in the first place. Changing that is a bigger (but planned!) project, though.
@tux0r well, I wouldn't call it that. Referring to devices by UUID seems safer and more stable. The partitions have unique IDs, we should use them. I'm not sure if systemd made the change, but it changed at some point in the "recent" past, yes.
Welcome to the 8th Layer of Madness
Most topics are related to Linux, Anime, Music, Software and maaaany more