ReclaiMe Data Recovery Training

RAID Recovery Course - Parity Analysis Test

Choose the property of XOR function due to which "you do not need to know the parity location when reconstructing a missing disk"

A XOR 0 = A
A XOR A = 0
A XOR B = B XOR A

Choose the correct statement

A XOR 0 = 1
A XOR 0 = A
A XOR 0 = 0

Choose the property of XOR function due to which "mirrors are always even"

A XOR 0 = A
A XOR A = 0
A XOR B = B XOR A

Choose the correct statement

A XOR A = 0
A XOR A > 0
A XOR A < 0

Look at the picture on the right and guess a RAID level

4-disk RAID 5 with one disk missing
3-disk RAID 5 with a hotspare
full 4-disk Promise RAID6 or full 4-disk RAID5

Parity test for a Promise RAID6 gives:

0% parity in full disk set and 0% parity in all combinations with one disk excluded
0% parity in full disk set and 100% parity in all combinations with one disk excluded
100% parity in full disk set and 0% parity in all combinations with one disk excluded

A row of [A,B,P] blocks is even if

A XOR B XOR P = 1
A XOR B XOR P = 0

Look at the picture on the right and guess the possible RAID level

Full RAID 5 with a hotspare
RAID 6 with a missing disk
RAID 5 with a missing disk
Full RAID6

Given that P is a parity block calculated over A and B data blocks

A XOR B XOR P = 1
A XOR B XOR P = 0

What is calculated in parity analysis?

percent of parity matches in disk pairs
percent of zero rows in disk set
percent of parity matches in disk set

Next lesson - Entropy analysis

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