Raid

9. What are the most common sources of problems with RAID?
In SCSI RAID the most common source of a wide variety of symptoms, including data loss, is incorrect cabling and termination. Use good quality cables which are no longer than absolutely necessary. Provide good active termination at the end of the SCSI bus. Use a separate terminating plug rather than using the termination on the hard drive, to avoid loss of termination if that drive fails or is removed.

Resource conflicts are another common source of problems. Incorrect interrupts or no interrupt assigned, onboard controller chips which have not been disabled when not in use, non-compliant motherboards, and so on, can all result in system lockups, installation aborts, and generally erratic behavior. Drive mismatches can cause problems with the array and its performance. Ideally, all the drives in the array should be identical, including the firmware version on the drive itself, since different versions of the drive firmware code can result in differences in access speed, queuing algorithms, and head movement optimization. Most disk manufacturers will provide firmware updates if multiple versions have been released over the life of a particular model.