Two hard drives?

[lorizzle]

I looked at the high-end performance sticky in the "build your own pc" forum, and I was wondering why the author included in his post two hard drives. Can someone enlighten me? Thanks!

[RickyTick]

The 2 hard drives were listed to provide the option of using them in a Raid set up, or to simply have additional storage space.

[chronicbucks]

can you expalin to me what exactly is raid??

god im a noob

[The Wise Monkey]

Hey, if you don't know you don't know. :)

RAID stands for Redundant Array of Independent Disks. It is basically a way of writing your data to more than one hard drive at a time. An array of disks is just the name for a group of hard drives.

RAID 0 requires two or more hard drives and is where data is written across all drives sequentially. So if you downloaded a 30MB file using an array with three drives, each drive would get 10MB each - this is called striping. Your OS sees this array as only one hard drive, so it can read and write from it with no problem. RAID 0 is mainly used for performance - since you are reading and writing to multiple drives, you speed up transfer rates by about 25% for two drives, and increasing amounts the more drives you add to the array. The downside to RAID 0 is that if one of the hard drives fails, you will lose all your data.

RAID 1 requires an even number of hard drives, and is where the same data is written to all hard drives simultaneously so you have two copies of everything - this is called mirroring. This offers much better data security because if one hard drive fails, you can just replace it immediately with one of the others because they will be identical.

You can also have combinations of these two - RAID 0+1 is where you have a RAID 0 array which is then mirrored, and RAID 1+0 is when you have a RAID 1 array which is then striped. Both of these require at least 4 hard drives.

There are more types of RAID array possible, such as RAID 5, but these are used much more in industry as opposed to home use.

Hope that makes sense. :)

[piikea]

That's a nice, succinct explanation of Raid. I haven't found the mentioned sticky in the initial post in this thread but was wondering:

for a Raid 1 set up w/ 2 HD's, do they need to be:
a.) same size? (& If so, I'd presume if partitioned they'd have to be done so in the same partition sizes?)
b.) same spec's (RPM, transfer rate, cache, etc)?