And of course, if your server dies, then the array can be mounted on any other box with the same OS and you can retrieve data from it -- which is far more difficult if a hardware RAID controller dies, in which case you might need the same firmware revision etc., and possibly onboard controller config info.
Funny story about that: In 1990 I installed a Compaq systempro for Hechinger's that cost over $100,000. Had a full compliment of memory, max internal disk on the ATA controller, and two external boxes of disks with the smart SCSI-ish controller. Massive system running Sybase SQL. Designed to replace a 24*7 mainframe and expected to be up all the time.
Got a call 2 months later: The system had blown a hole in one of the disk controllers and was down. Called Compaq, they got someone on a plane with a spare controller from the west coast and I drove out to meet them in the middle of the night so we could get the system up by morning.
That was pretty insane. And pointed out that "mainframe" PC's didn't have anywhere near the redundancy or support of true mainframes.
C
