1. RAID Arrays A short summary for TAFE

2. What is a RAID A Raid Array is a way of protecting data on a hard drive by using “redundancy” to repeat data across a number of drives. If one drive fails, the data can be retrieved (in most cases)

3. Types of RAID arrays JBOD (Just a bunch of Disks). Technically not a RAID array, as there is no redundancy, a group of smaller disks joined together to make one big volume.

4. RAID 0 Again, not technically a RAID Array. No redundancy, but allows for data to be “striped” across two or more disks. (Very fast transfer) Loss of one disk is fatal to the system

5. RAID 1 Data is duplicated across two disks. Loss of one disk is not fatal, but there is huge redundancy. Two 300GB HDDs in a RAID 1 array will give a 300GB volume, so you’ve halved your space…

6. RAID 3 Several disks with data striped plus a parity disk (using block level parity and hamming codes) Usually the parity disk is the first to fail, so not used.

7. RAID 4 An improvement on RAID 3, but not used much, for the same reason: parity disk is usually the first to fail.

8. RAID 5 This is the commonly used array type. Three or more disks with striping and block level parity shared across all disks. Four 300GB disks show one 900GB volume (1-n drives)…

9. Other fun RAID Arrays. What is the purpose of each?

10. More arrays. What is the purpose of each?