Know Your RAID Terms

Know Your RAID Terms

You will not be doing this with your RAID.

 

On paper, RAID stands for Redundant Array of Inexpensive/Independent Disks/Drives. In practice, RAID takes many forms. Here's your cheat sheet to the ground rules of RAID.

 

THE TWO MAINS TYPES OF RAID ARE...

Striped. This type theoreticallydoubles the data-throughput speed by writing data to two (or more) drives simultaneously, in stripes made up of 32K to 256K blocks of data. Two 100 GB drives create a 200GB striped volume (if you use different-size drives, you get double the smaller one's capacity.

 

Mirror. Simply allows one drive to mirror another, so you still have a copy of your data if either drives fails.

 

TWO MORE IMPORTANT TERMS...

Set. Multiple drives in a RAID constitute a set.

 

Volume. A striped RAID set apperas on the Desktop as a single volume.

 

THE LEVELS OF RAID ARE...

Raid 0. A striped set.

 

Raid 1. A mirrored set.

 

Raid 2. Data striping at the bit level (there are 8 bits in a byte, 8,192 in a kilobyte) - this is low-level stuff.

 

Raid 3. Data striping at the byte level, storing byte-parity (that is, data-reconstruction) information on a separate drive.

 

Raid 4. Block-level striping, requiring a dedicated parity drive.

 

Raid 5. Block-level striping with a parity block on each stripe.

 

Raid 6. Block-level striping with two parity blocks on each stripe.

 

Raid 10. Mirroring multiple striped volumes.

 

And the list goes on...but 0, 1, and 5 are the most common.

 

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