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Originally Posted by GrouchyAdmin
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.
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That sounds more like RAID3, which has a single dedicated parity disk. RAID5 stripes parity (as well as data) across all of the disks in the array.
Quote:
Originally Posted by MrMaxwell
What would it be called if you had two raid 0 arrays mirrored? That'd be a more reliable setup, right, but not necessarily "twice" as reliable, though, right?
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This is RAID0+1, which is striping two drives, then mirroring the stripe. It's better to do it the other way around (RAID10): mirror two drives, then stripe the mirror. Speed and performance wise there's little difference between the two, but a 4 drive RAID10 will rebuild twice as fast than a 4 drive RAID0+1 if a drive has to be replaced.
RAID0+1/RAID10 offers the speed benefit of striping, and also better average seek time if your controller is smart enough to properly load balance by sending a request to the drive whose head is likely to be closest to the sector it wants to access. Obviously RAID0+1/RAID10 also offers the benefit of mirroring so a single drive failure will not kill your array. It can actually handle one more failure depending on the position of the drive in the mirror. (After the first drive fails you have a 50% chance of losing the array when the SECOND drive fails)
Anyway... RAID is for uptime, not for reliable storage. You need a backup for that. :D If you're comfortable with it, you can use RAID0 or JBOD for your backup volumes, since they don't technically need to be fault tolerant. Depends how paranoid you are, and how important your data is.
BTW... Pentium Ds... old Xeons... with the amount of power those things take you might actually save money by upgrading to something more efficient.
I replaced a Pentium D 830 with a Celeron E1400 that consumes about half the power. If that box ran at 100% load 24/7/365 then it would save something like $USD75 worth of electricity in a year. Of course it doesn't run at 100% load, but it's still saving at least
