I used to manage Microsoft SQL Server installations. Now I'm up against a MySQL 5.1 server.
On MSSQL, I remember databases have transaction log files which grow larger and larger as transactions occur. If you don't truncate the files every now and then, you will eventually run out of disk space. So even if you compact your databases by deleting old rows, disk space will be running out.
I wonder if MySQL behaves similarly and what steps I need to take to make sure that disk space won't get depleted.