I have a 72GB core disk, and have 4 MDs currently defined. A runaway process producing lots of coredumps can fill up any size disk rapidly. Other than that, I liked my 10k RPMs 72GB drive as my core drive, and only replaced it with an SSD due to hardware issues. The SSD now is a 120GB drive, but I partitioned it to only used as much as space as the former drive had, so I can swap it back when it comes back from repair.