We have three (nearly) identical boxes, all with fresh installs of RH6.2. They are all dual PIII 550 Copermines with 4 drive SCSI RAIDs. One of them has an IDE drive to boot from and a software RAID. It works great. Another has a Mylex AccelRAID 150 card. It boots from the RAID, and also works great. The third has the same Mylex card, boots from the RAID just fine, but all disk operations are slow as dirt. Opening the case, the access lights on all the drives are constantly flickering, and the drives are audibly grinding - even when there is no activity on the machine. The Mylex cards are all flashed the latest version of the Mylex BIOS and whatnot. At this point the RAID is pretty much worthless - besides being several times slower than your average IDE drive, it is probably likely to blow a drive within a few months just because it is grinding itself to death 24 hrs a day. Anyone encounter this before?
This is probably a driver/firmware bug. I encourage you to contact the author of the Mylex driver.