1. Department of Electronics Advanced Information Storage 18 Atsufumi Hirohata 17:00 05/December/2013 Thursday (P/T 006)

2. Quick Review over the Last Lecture Millipede memory : * http://nanotechweb.org/cws/article/tech/36334; * http://www.wikipedia.org/ Nano-RAM : Floating junction gate :

3. 18 RAID and Cloud Computing Cloud computing Storage technology RAID Parity error detection Data striping Data mirroring

4. Cloud Computing * http://www.wikipedia.org/ In 2006, Eric E. Schmidt (Google) first introduced the phrase : *

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

6. Cloud Companies * http://cloudtimes.org/2011/11/30/top-paas-saas-and-iaas-cloud-companies-by-cloudtimes/

7. Cloud for Mobile Devices Mobile data are stored in servers in cloud : * * http://www.ubergizmo.com/2011/10/iphone-4s-review/ 120 iPhones 1 server in cloud Can store data from 8 iPads

8. Storage Technology In 1987, David Patterson, Garth A. Gibson and Randy Katz defined : * * http://www.wikipedia.org/; ** http://bnrg.cs.berkeley.edu/~randy/ 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 * http://www.wikipedia.org/ 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

10. Parity Error Detection * http://www.computerhope.com/jargon/p/parity.htm 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

11. Data Striping * http://www.ni.com/white-paper/6253/ja/ Data stream is distributed to several drives : *

12. RAID 1 * http://www.wikipedia.org/ 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

13. Data Mirroring * http://www.openminds.co.uk/windows-solutions/data-replication/data-replicationmore-information.html Data are duplicated onto another drive(s) : *

14. RAID 2 * http://www.wikipedia.org/ 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

15. RAID 3 * http://www.wikipedia.org/ 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

16. RAID 4 * http://www.wikipedia.org/ 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. RAID 5 * http://www.wikipedia.org/ 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

18. RAID 6 * http://www.wikipedia.org/ 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

19. RAID 10 * http://www.wikipedia.org/ 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