Your problem is related to filesystem, not disks. For some reasons
your filesystem (on top of raid) was not properly unmounted: assuming
you didn't hard-reboot your server, this happened to me whith some IDE
devices which lied about commit of write operations. Even if my server
was rebooted normally, filesystem and disks were left in an
inconsistent state. Better SCSI disks solved the problem. Hardware has
become more crappy day by day.
RAID in general keeps your system up if a disk fails, not if
filesystem on top of it screws up.
f.