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1. RAIDs

		N disks disk = address % N offset = address / N
		disk1 = (address % (N/2)) * 2,   disk2 = disk1 + 1 offset = address / (N/2) write to both disks, read from even-numbered disk for even offsets, read from odd-numbered disk for odd offsets.

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2. Comparison

N disks

Each disk: B blocks, S MB/sec sequential, R MB/sec random, T sec latency

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3. Exercises - RAID Level 0

Exercises from the book using raid.py:

numDisks 4
chunkSize 4k

$ python ./raid.py -n 4 -R 21 -L 0

LOGICAL READ from addr:17 size:4096
  Physical reads/writes?

LOGICAL READ from addr:8 size:4096
  Physical reads/writes?

LOGICAL READ from addr:10 size:4096
  Physical reads/writes?

LOGICAL READ from addr:16 size:4096
  Physical reads/writes?

$ python ./raid.py -n 4 -R 21 -L 0 -r

LOGICAL OPERATION is ?
  read  [disk 1, offset 4]

LOGICAL OPERATION is ?
  read  [disk 0, offset 2]

LOGICAL OPERATION is ?
  read  [disk 2, offset 2]

LOGICAL OPERATION is ?
  read  [disk 0, offset 4]

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4. Exercises - RAID Level 1

$ python ./raid.py -n 4 -R 21 -L 1

LOGICAL READ from addr:17 size:4096
  Physical reads/writes?

LOGICAL READ from addr:8 size:4096
  Physical reads/writes?

LOGICAL READ from addr:10 size:4096
  Physical reads/writes?

LOGICAL READ from addr:16 size:4096
  Physical reads/writes?

$ python ./raid.py -n 4 -R 21 -L 1 -r

LOGICAL OPERATION is ?
  read  [disk 2, offset 8]

LOGICAL OPERATION is ?
  read  [disk 0, offset 4]

LOGICAL OPERATION is ?
  read  [disk 1, offset 5]

LOGICAL OPERATION is ?
  read  [disk 0, offset 8]