1. RAID CS5493/7493

2. RAID : What is it? Redundant Array of Independent Disks configured into a single logical storage unit.

3. RAID : Implemented with current disk storage technologies: – SATA Serial Advanced Technology Attachment – SCSI Small Computer System Interface – SSD Solid State Disk

4. Storage Performance Factors

5. Capacity

6. Storage Performance Factors Capacity Noise Level

7. Storage Performance Factors Capacity Noise Level Power Consumption

8. Storage Performance Factors Capacity Noise Level Power Consumption Data Transfer Rate

9. Storage Performance Factors Capacity Noise Level Power Consumption Data Transfer Rate Reliability

10. Storage Performance Factors Capacity Noise Level Power Consumption Data Transfer Rate Reliability Temperature

11. Performance Pyramid Fast Cheap Good S-S, Steady State

12. Performance Pyramid Fast – Faster IO transfer rate Cheap – Lower cost per GB Good – more reliable, – lower temp, – less noise – Less power consumption

13. Performance Pyramid FastCheap S-S Good

14. Technology Comparison Single Unit Storage Devices $/GBMTBFIO RateNoisePower SATA-HDD~$0.05< 90 K-hrs< 100 MB/s~40dB2.5-10W SASCSI-HDD~$1.00~ 90 K-hrs~ 100 MB/s~50dB10W SATA-SSD~$0.50~ 90 K-hrs~ 500 MB/s> 0 dB< 2.5W

15. RAID Purpose RAID can improve – Reliability (except level-0) – Data Transfer Rates through parallelism (faster than the single unit rates)

16. RAID Purpose RAID can improve – Reliability – Data Transfer Rates RAID sacrifice – Cost per GB increases

17. Common RAID Levels RAID-0 RAID-1 RAID-3 RAID-5 RAID-6 RAID-1+0 RAID-0+1

18. RAID-0 Striped, no mirror, no parity IO Speedup bounded by number of drives and Amdahl’s Law. No fault tolerance Minimum of 2 drives

19. RAID-1 No Striping, no parity, uses a mirror 2 drives (data and mirror) Fault tolerance is one

20. RAID-3 Byte level striping and Dedicated parity drive – Parity uses the logical exclusive-or operation n-1 IO speed-up limit Minimum of 3 drives required. Fault tolerance is one

21. RAID-5 Block level striping Distributed parity Parallel IO data transfer across the array Minimum of 3 drives required Fault tolerance is one

22. RAID-6 Block level striping Distributed and redundant parity Parallel IO data transfer across the array. Minimum of 4 drives required Fault tolerance is two

23. RAID-1+0 Combination of RAID-1 and RAID-0 Logical drives are physical pairs configured as RAID-1 devices The logical drives are then configured as a stripe. Fault tolerance is ≥ 1.

24. RAID-0+1 Combination of RAID-1 and RAID-0 A stripe of drives is mirrored Fault tolerance is ≥ 1.

25. Relative Reliability of RAID Class exercise