Originally Posted by yucky
Which SW Raid gives the best reliability and performance?
RAID-6 has the best reliability and lowest performance. (Reads are actually high performance, but writes are REALLY poor.) It supports two drive failures, but software implementations are not common.
RAID-5 is similar to RAID-6, but supports just one drive failure. It is also the most efficient RAID level, requiring just one drive's worth of overhead. (RAID-6 is two.)
RAID-10 has good reliability and best performance. It supports one drive failure per RAID-1 pair. In other words, half the drives could fail and the array would still work, assuming they were the correct drives. If not, a two drive failure can bring down the array. Also, RAID-10 is the least efficient RAID level, requiring half your drives to be used for overhead.
(BTW, I'm assuming that you're asking about redundant arrays, and not RAID-0.)
Also it's important to point out that software RAID is not bootable, it can't support write-back cache and it can take a lot of CPU cycles. Hardware RAID with battery-backup avoids all these problems, but of course costs more.
With all this said, do you really need the redundancy offered by RAID? Do you care that your media library is taken down when a drive fails? If you're not serving video to a hotel, etc., then losing access isn't a big deal. Just tell your family to watch a DVD. It's not like you're going to actually lose your data, because it's backed up, right? Remember, RAID isn't a backup strategy - it's an "always available" strategy. That's why I use RAID-0 for my media, and I backup to cheap, external USB drives. And I try to keep those USB drives offsite, at my office or wherever, just in case the house burns down - knock on wood.