Quote:
Originally Posted by MrMaxwell
I'm very new to raid but I like it
Just a bunch of disks, it becomes a big mess fast... doesn't it?
And raid 5 is two raid0s mirrored with a spare in case of a failure?
I know that raid 0 is volatile but you probably should just treat it like any other drive.. drives fail.. so to me two as one is just one drive .. maybe think of that drive as being made by some off brand because it's half as trustworthy
Is it really 2ms difference in the seek time? That's significant!
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Not quite.
RAID0 is just 'treating it all as one disk', basically. RAID5 segments different drives (at least two) and uses another for parity. If one fails (and eventually, they all do), you can restore all of the data by the pre-existing content that is there and the parity. In the event the parity drive fails, it just rebuilds that. So, it'll take you 3 disks to make 1, but when one dies, you're only slowed down - you're not fucked.
You can't use 'two as one' as an analogy because EVERYTHING now has at least twice the amount of failure probability - two spindles, 2 controllers, (and it should be 2 different power rails, at least), etc, etc.
RAID0, if you have 2 drives, one fails - there went half the filesystem. JABOD also suffers from this, but JABOD isn't quite as bad; RAID 0 requires everything be matched up size-wize - JABOD you can just throw anything together - and unless you totally fuck up, you may be able to stitch it back together. Some filesystems can 'heal' and work better with a JABOD system - ZFS and Reiser are semi-capable of this.
At the very least, I'd suggest RAID1, where it's just a mirror of the same content spanned across two drives. One dies, hope to hell the other one isn't.
On average, RAID0 does lookup faster, and that average with 360u SCSI w/ huge cache was about 2ms. With SAS/SATA, it's probably similar. May shave 4 seconds off of the wait time for shit to load, and you just lost your life's work. What a tradeoff!