Hey.. if you were going to load down a 2U with 3 drives in order to save space. How could you allow the server to automatically distribute the space as needed, i mean account setup will automatically go to the main drive, so when that drive is full, then what?
How could i manage all three drives automatically to be divided and used appropriately and still be able to move accounts around as i see fit?
I would recommend using Raid 5 if you are going to use 3 drives. For example, if you had 3 36G hard drives, you would end up with 72G of usable space and the remaining 36G of space is used for holding parity information in the event of drive failure.
Raid 1 is drive mirroring. With drive mirroring you must have an even number of drives. Using your example, you would need 4 120G drives and this would yield 2 redundant 120G volumes with good fault tolerance. Using raid 5, with 3 120G volumes you would have 240G usable space and would have redundancy such that if you lost one of the three drives, your server would still run and you would NOT lose data. I did a search on google and found a decent site that explains some of this.
(Disclaimer: I don't actually run RAID, so what I speak from is just what I've learned over the years.)
I've always considered RAID 1 to be some sort of "outcast" -- I believe every other RAID level exists for redundancy in the event of a failure. RAID 1 just gives you really fast drives. The problem is that if a single drive in your RAID 1 stripeset fails, you apparentely lose the whole disk set -- you could almost say that RAID 1 increases your chance of failure over "JBOD" (Just a Bunch Of Disks), whereas the other RAID levels are designed so if a single disk fails, you chuck it, pop a new one in, and "rebuild" the disk's contents.
Fog I think your talking about Raid 0 Striping that is for speed that does double your chance's of failuse.... Raid 1 is mirroring and just keeps an exact copy of the hard drive on another drive. It won't speed up the hard drive at all.
That's one of the basic premises of RAID -- it appears as one 'logical unit,' so you don't have to manually make backups or anything. Exactly what ends up on what drives depends on what type of RAID you're running, but the whole point of RAID is that it automatically 'copies' stuff and all.
Raid 1 is drive mirroring. With drive mirroring you must have an even number of drives. Using your example, you would need 4 120G drives and this would yield 2 redundant 120G volumes with good fault tolerance
4 x 120G drives in RAID 1 is just 120G mirrored on all 4 drives. You can have 3 drives in RAID 1. What you get is same 120G mirrored on 3 drives.