1 / 22

RAID Technology

RAID Technology. CS350 Computer Organization Section 2 Larkin Young Rob Deaderick Amos Painter Josh Ellis. Overview. Background Term coined by researchers at UC-Berkeley R edundant A rray of I nexpensive D isks Basics of RAID Disk arrays Logical/physical

gurit
Download Presentation

RAID Technology

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. RAID Technology CS350 Computer Organization Section 2 Larkin Young Rob Deaderick Amos Painter Josh Ellis

  2. Overview • Background • Term coined by researchers at UC-Berkeley • Redundant Array of Inexpensive Disks • Basics of RAID • Disk arrays • Logical/physical • Controller (software/hardware)

  3. Techniques/Methods • Mirroring • Parity 10101010 XOR 11111111 = 01010101 11111111 XOR 01010101 = 10101010 10101010 XOR 01010101 = 11111111

  4. Techniques/Methods (cont’d) • Striping

  5. RAID 0 • Uses striping • I/O performance gain • No Data redundancy • Not fault tolerant • Not considered “true” RAID

  6. RAID 1 • Uses mirroring • Also known as duplexing • Fault tolerant • High Disk overhead • Mirroring typically handled system software • Simplest RAID design

  7. RAID 2 • Error Detection and Correction • Parity and Hamming Code • Used to identify and correct errors • Hamming Code • Uses parity bits to verify data integrity • Parity bits signify oddness of data bits • ECC (Error Correction Code)

  8. RAID 2 Characterized by: • “On the fly” data correction • High Ratio of Data disks to ECC disks • Not a commercially viable solution • High Costs Involved

  9. RAID 3: XOR • Exit Hamming Code, Enter XOR (eXclusive OR) • XOR in Action: 01012 XOR 00112 = 01102 If ????2 XOR 11002 = 01102, Then 11002 XOR 01102 = ????2 = 10102 Thus we can use XOR results to recover lost data

  10. Advantages: High Read/Write Transfer Rates Disk failures don’t slow the system Low Ratio of Data Disks to Parity Disks Disadvantages: Transaction rate slowed by Parity Disk Complex Controller Design Software Implementation Resource Intensive RAID 3: Pros and Cons

  11. RAID 3: Uses • Video Production • High-end Video and Image Editing • Other uses that require high throughput of data

  12. RAID 4 • Offshoot of RAID 3 • No Striping, Entire files written to individual disks • Parity Data created on a sector-by-sector basis

  13. Advantages: Very high read rates Multiple files read at once Uses: Web Servers, and other high read, low write situations Disadvantages: Very slow write rates Even small writes fill up parity write queue Inefficient data recovery Even more Complex Controller Design than RAID 3 RAID 4: Pros, Cons, and Uses *Has most of the other Advantages and Disadvantages of RAID 3

  14. RAID 5 • Highest Read data transaction rate • Medium Write data transaction rate • Most complex controller design • Used For Server Applications.

  15. RAID 6 • Fault tolerance • Very complex controller design • Very poor write performance

  16. RAID 7 • Extremely high cost per MB • Fast access times • Improved write performance with increasing number of drives

  17. RAID 10 • Uses multiple (mirrored) RAID 1 in a single array • Data striped across all mirrored sets • Very high fault tolerance • High performance rate

  18. RAID 10 Characterized by: - each drive duplicated - high implementation cost

  19. RAID 53 • Consists of a striped array made up of RAID 3 segments • Very expensive • Achieves high rate of I/O

  20. RAID 0+1 • Acts as a mirrored array whose parts consist of RAID 0 arrays • Very expensive • Works well in handling images • very high data transfer rate

  21. RAID 0+1 - Not great reliability - one disk failure leaves you left with only the characteristics of a striped array (no fault tolerance)

  22. Conclusion • Grown more complex • Large price range • Huge step forward for industry • Not for the masses yet

More Related