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RAID 1+0 All the way! Re:Performance/Raid question large databases ~Umberto Nongeroson 1.May.03 05:25 PM a Web browser Domino Server All ReleasesLinux - RedHat
Here's a quick overview of your RAID architectures:
Raid 0 - AKA "Striping"
METHOD: Lumps multiple drives together to act as one large volume.
STORAGE: SUM(Disk1Size, Disk2Size, Disk3Size, etc.)
PROS: No wasted space. Read speed is typically great, as is write speed.
CONS: No redundancy.
Raid 1 - AKA "Mirroring"
METHOD: 2 identical drives -- each drive is an identical "mirror" of the other.
STORAGE: (SizeOfOneDisk)
PROS: Good redundancy, as in order to have complete failure you must have a drive *and* it's mirror drive fail simultaneously. Read speed is typically great (the controller has 2 different drives to read from for any one piece of data -- usually it will choose the one with the least amount of seek involved). Write speed is good.
CONS: You only get 1/2 the storage of your total drive space.
Raid 5
METHOD: 3 or more identical drives configured using a "parity" configuration.
STORAGE: (NumberOfDisks - 1) * SizeOfOneDisk
PROS: Gives good redundancy without sacrificing much in the way of storage. A 5-drive volume only "loses" 1 drive's-worth of storage. Any single drive can fail and the volume data is not compromised.
CONS: Read speed is so-so -- not horrible, but usually slower than say, RAID 1. Write speed, on the other hand, is ABYSMAL. Every write causes a parity calculation plus a write to EVERY drive in the volume.
Raid 1+0
METHOD: Takes multiple RAID 1 volumes (i.e. pairs of "Mirrored" drives) and "stripes" them into one large volume.
STORAGE: SUM(SizeOfOneDiskInPair1, SizeOfOneDiskInPair2, etc.)
PROS: Same good redundancy as RAID 1 -- a drive *and* its mirror must fail simultaneously. Read speed is great, as per RAID 1, write speed is great also.
CONS: You only get 1/2 the storage of your total drive space. Controllers that can handle this configuration are usually a bit more expensive.
Raid 1+0 is MUCH faster than Raid 5. If you need speed (which it sounds like you do) and can handle the sacrifice in storage space, I would definitely go that route.
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. . RAID 1+0 All the way! Re:Performanc... (~Sanjay Quettum... 1.May.03) 
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