1. Information Storage and Spintronics 16
Atsufumi Hirohata
Department of Electronic Engineering
09:00 Tuesday, 20/November/2018 (J/Q 004)

2. Quick Review over the Last Lecture
Millipede memory :
Nano-RAM :
Floating junction gate : * *

3. 16 RAID and Cloud Computing
Storage technology
RAID
Parity error detection
Data striping
Data mirroring

4. Cloud Computing
In 2006, Eric E. Schmidt (Google) first introduced the phrase : * * 4

5. Cloud Layers Cloud computing extends the existing concepts : *
SaaS : Software as a service
PaaS : Platform as a service
IaaS : Infrastructure as a service * 5

6. Cloud Companies * 6

7. Cloud for Mobile Devices
Mobile data are stored in servers in cloud : *
1 server in cloud
Can store data from
120 iPhones
8 iPads * 7

8. Storage Technology
In 1987, David Patterson, Garth A. Gibson and Randy Katz defined : *
Redundant array of inexpensive (independent) disks (RAID)
combines multiple disk drive components into a logic unit
Data distributed across the drives
Levels of redundancy and performance required
→ RAID 0 ~ 10 * **

9. RAID 0 Block-level striping without parity or mirroring : *
Minimum number of drives : 2
Space efficiency : 1
Fault tolerance : 0
Array failure rate : 1 – (1 – r) n
Read performance : nX
Write performance : nX * 9

10. Parity Error Detection
Parity bit is used for error detection : *
Even / odd parity
Binary stream contains even / odd number of “1”.
For example, serial data transfer uses
Binary stream : 7 digit + Parity : 1 digit * 10

11. Data Striping Data stream is distributed to several drives : ** 11

12. RAID 1 Mirroring without parity or striping : *
Minimum number of drives : 2
Space efficiency : 1 / n
Fault tolerance : n – 1
Array failure rate : r n
Read performance : nX
Write performance : 1X * 12

13. Data Mirroring Data are duplicated onto another drive(s) : ** 13

14. RAID 2 Bit-level striping with dedicated Hamming code parity : *
Minimum number of drives : 3
Space efficiency : 1 – 1 / n log 2 (n – 1)
Fault tolerance : 1 drive depending on the corresponding data and parity conditions
Array failure rate : variable
Read performance : variable
Write performance : variable * 14

15. RAID 3 Bit-level striping with dedicated parity : *
Minimum number of drives : 3
Space efficiency : 1 – 1 / n
Fault tolerance : 1 drive
Array failure rate : 1 – (1 – r) (n – 2) / 2
Read performance : (n – 1 )X
Write performance : (n – 1 )X * 15

16. RAID 4 Block-level striping with dedicated parity : *
Minimum number of drives : 3
Space efficiency : 1 – 1 / n
Fault tolerance : 1 device
Array failure rate : 1 – (1 – r) (n – 2) / 2
Read performance : (n – 1)X
Write performance : (n – 1)X * 16

17. RAID 5 Block-level striping with dedicated parity : *
Minimum number of drives : 3
Space efficiency : 1 – 1 / n
Fault tolerance : 1 device
Array failure rate : 1 – (1 – r) (n – 2) / 2
Read performance : (n – 1)X
Write performance : (n – 1)X * 17

18. RAID 6 Block-level striping with double-distributed parity : *
Minimum number of drives : 4
Space efficiency : 1 – 2 / n
Fault tolerance : 2 device
Array failure rate : 1 – (1 – r) (n – 3) / 2
Read performance : (n – 2)X
Write performance : (n – 2)X * 18

19. RAID 10 Mirroring without parity and block-level striping : *
Minimum number of drives : 4
Space efficiency : 2 / n
Fault tolerance : 1 device
Array failure rate :
Read performance : nX
Write performance : (n / 2)X * 19

20. Cloud Servers at Norther Isles
864 servers installed under the sea near the Orkney Islands : *
Sea water is used for cooling servers. * 20

21. Coarse Wavelength Division Multiplexing (CWDM)
Data transfer via an optical fibre developed by hp : * * 21

22. CWDM on a Chip The Machine component : ** 22