Originally posted by: Sunner
Originally posted by: Sahrin
RAID 5 is where it's at. Fault prtection across all volumes, hot-swapping, and speed increases as you add drives. Assuming a controller with unlimited channels, and unlimited number of drives is possible, and speed increases with every drive you add (though the law of dimishing returns applies). RAID 5 combines the best features of both 0 (speed) and 1 (fault protection) with hot-swapping in an array.
Hotswapping has nothing to do with RAID-5, or any RAID level for that matter, except possibly 0 where it would be rather unwise.
It has to do with the interface.
Also, RAID5 has worse write performance than RAID0 (as the number of drives in the RAID5 increases, this penalty becomes less severe, but it's always there), worse read perfomance than a RAID1, and worse fault tolerance than RAID1 (any two disks failing ruins the array; RAID1 can lose all but one disk). Its space utilization is better than RAID1 but worse than RAID0 (again, dependant on the number of drives in the array for RAID5).
It's a compromise. A very good one for most situations, but still a compromise. It is, however, generally superior to RAID0+1 for 4-drive arrays (0+1 has better read performance, but only 50% space utilization as compared to 75% for RAID5), and unless you're super-paranoid about disk failures, it is usually the best choice for RAID arrays of >4 disks (unless your I/O is very, very read-heavy; RAID1 and 0+1 lose too much write performance as the number of disks grows).