I have a relatively small and happy MySQL 5.1 database living on a FreeBSD 7.1 64bit install. Because of incompatibility with our backup software and FreeBSD, I have to move the databases to a Linux server.

Since we run Debian on everything else here I'm going to settle for that. The big question is if I should run 32bit or 64bit. It's a virtualized enviroment, so hardware doesnt play a role in this.

Will I get any performance gain (or loss) by using 64bit linux+64bit MySQL with little memory assigned (lets say 512M to be extreme)? Should I just use 32bit until the day I need to assign more than 2GB RAM to MySQL (PAE does not help, 32bit MySQL can not use more than 2GB)?