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Performance Evolution of
RAID
PresentationTopic
Member:
• Zubair Hossain (13103037)
Group: Processor
1. What is RAID?
2. Importance of RAID
3. Concept about RAID
5. Standard Raid Level
6. Nested Raid Level
7. Implementation...
WHAT IS RAID?
RAID MEANS REDUNDANT ARRAY OF INDEPENDENT DISKS.
IT IS ALSO CALLED REDUNDANT ARRAY OF INEXPENSIVE DISKS.
IMPORTANCE OF RAID
1. RELIABILITY
2. REAL-TIME DATA RECOVERY WITH UNINTERRUPTED ACCESS WHEN A HARD DRIVE FAILS
3. SYSTEM U...
CONCEPT ABOUT RAID
THE TWO FUNDAMENTAL RAID CONCEPTS :
Data
Redundancy
Data
striping
DATA REDUNDANCY
REDUNDANCY GIVES US THE ABILITY TO HAVE A DRIVE FAIL
WITHOUT LOSING VALUABLE DATA
There are Two Type of Da...
DISK MIRRORING
• KEEP TO COPIES OF DATA ON TWO SEPARATE DISKS
• GIVES GOOD ERROR RECOVERY
• IF SOME DATA IS LOST, GET IT F...
DATA PARITY
• WAY TO DO ERROR CHECKING AND CORRECTION
• ADD UP ALL THE BITS THAT ARE 1
• IF EVEN NUMBER, SET PARITY BIT TO...
DATA STRIPING
DATA STRIPING IS THE TECHNIQUE
OF SEGMENTING LOGICALLY
SEQUENTIAL DATA, SUCH AS A FILE,
SO THAT CONSECUTIVE ...
STANDARD RAID LEVEL
RAID – 0 (STRIPING)
RAID – 1(MIRRORING)
RAID – 2(Redundancy through Hamming code)
RAID – 3(Bit Interle...
RAID-0
DATA ARE STRIPPED ON ALL DISKS
OFFER PERFORMANCES
NO REDUNDANCY
2 DISKS MINIMUM, MAXIMUM DEPENDING OF RAID CONTROLL...
RAID-1
DATA MIRRORED (DUPLICATED) ON SECOND HARD DISK
OFFER REDUNDANCY
EQUIVALENT OF ONE DISK SPACE LOST FOR REDUNDANCY
ON...
• STRIPES DATA AT THE BIT LEVEL
• USES A HAMMING CODE FOR ERROR CORRECTION.
• THE DISKS ARE SYNCHRONIZED BY THE CONTROLLER...
RAID-3
 RAID 3 IS CONFIGURED WITH AT LEAST THREE DRIVES
 TWO DRIVES CARRY THE DATA AND THE THIRD DRIVE CARRIES PARITY IN...
RAID-4
A RAID 4 USES BLOCK-LEVEL STRIPING WITH A DEDICATED
PARITY DISK.
OTHER ARE SAME AS RAID 3
 Stripes data and parity to generate redundancy.
 The parity is distributed through the stripe of the disk array.
 both...
RAID-6
 Data is striped across all disks (minimum of four)
 A two parity blocks for each data block (p and q in the
diag...
NESTED RAID LEVEL
LEVELS OF NESTED RAID, ALSO KNOWN AS HYBRID RAID COMBINE TWO
OR MORE OF THE STANDARD LEVELS OF RAID TO G...
Nested Raid Level
RAID-
(0+1) RAID-10 RAID-50 RAID-60
RAID (0+1)
• RAID-01 IS TECHNICALLY A
COMBINATION OF RAID-1 AND
RAID-0, INCLUDES BOTH
MIRRORING AND STRIPING, BUT
WITHOUT ...
RAID 10
IT USES RAID-1MIRRORING AND RAID-0
STRIPING, AND HAS BOTH SECURITY AND
SEQUENTIAL PERFORMANCE.
IT IS A STRIPED R...
RAID-50
• COMBINES MULTIPLE RAID 5 SETS
WITH RAID 0 (STRIPING).
• REBUILD TIMES ARE
SUBSTANTIALLY LESS THAN A
SINGLE LARGE...
RAID-60
• COMBINES MULTIPLE RAID 6 SETS WITH
RAID 0 (STRIPING).
• DUAL PARITY ALLOWS THE FAILURE OF
TWO DISKS IN EACH RAID...
IMPLEMENTATION OF RAID
• THERE ARE TOW TYPES OF RAID IMPLEMENTATION.
Software
Implementation
Hardware
Implementation
SOFTWARE IMPLEMENTATION
• SOFTWARE RAID CAN BE IMPLEMENTED IN A VARIETY OF WAYS: IN THIS CASE,
THE RAID IMPLEMENTATION IS ...
SOFTWARE IMPLEMENTATION
SOFTWARE BASED RAID:
• SOFTWARE IMPLEMENTATIONS ARE PROVIDED BY MANY OPERATING SYSTEMS.
• A SOFTWA...
HARDWARE IMPLEMENTATION
• A HARDWARE RAID SOLUTION HAS ITS
OWN PROCESSOR AND MEMORY TO
RUN THE RAID APPLICATION. IN THIS
I...
HARDWARE IMPLEMENTATION
HARDWARE BASED RAID:
• A HARDWARE IMPLEMENTATION OF RAID REQUIRES AT LEAST A SPECIAL-
PURPOSE RAID...
• The key to performance increases under RAID is parallelism. The ability to
access multiple disks simultaneously allows f...
• Mirroring: In Raid every piece of data is duplicated, stored on both drives. There's
absolutely no reason to access both...
• Mirroring: Mirroring improves positioning performance. However, once the
data is found, it will be read off one drive.
•...
• Decreasing Stripe Size: As stripe size is decreased, files are
broken into smaller and smaller pieces. This increases th...
Performance and Advantages
Comparison among RAID
Levels
RAID has been with us for about 20 years, but until only recently
it was the domain of big systems and deep pockets. Durin...
• 1. RAID for Enterprise Computing – Copyright @ VERITAS Software Corporation, 1999,
2000
• 2. RAID: High-Performance, Rel...
Performance evolution of raid
Performance evolution of raid
Performance evolution of raid
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Performance evolution of raid

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Performance evolution of raid is a presentation slide about RAID, Its classification, Importance,Concept about RAID,Standard Raid Level,Implementation of Raid, Performance and Advantages Comparison among RAID Levels.
Hope It will be helpfull..................

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Performance evolution of raid

  1. 1. Performance Evolution of RAID PresentationTopic
  2. 2. Member: • Zubair Hossain (13103037) Group: Processor
  3. 3. 1. What is RAID? 2. Importance of RAID 3. Concept about RAID 5. Standard Raid Level 6. Nested Raid Level 7. Implementation of Raid 8. RAID Performance Issue 9. Performance and Advantages Comparison among RAID Levels 10.Conclusion 11.References Index
  4. 4. WHAT IS RAID? RAID MEANS REDUNDANT ARRAY OF INDEPENDENT DISKS. IT IS ALSO CALLED REDUNDANT ARRAY OF INEXPENSIVE DISKS.
  5. 5. IMPORTANCE OF RAID 1. RELIABILITY 2. REAL-TIME DATA RECOVERY WITH UNINTERRUPTED ACCESS WHEN A HARD DRIVE FAILS 3. SYSTEM UPTIME AND NETWORK AVAILABILITY AND PROTECTION FROM LOSS PROTECTION AGAINST DATA LOSS 4. MULTIPLE DRIVES WORKING TOGETHER INCREASE SYSTEM PERFORMANCE
  6. 6. CONCEPT ABOUT RAID THE TWO FUNDAMENTAL RAID CONCEPTS : Data Redundancy Data striping
  7. 7. DATA REDUNDANCY REDUNDANCY GIVES US THE ABILITY TO HAVE A DRIVE FAIL WITHOUT LOSING VALUABLE DATA There are Two Type of Data Redundancy 1. Disk Mirroring 2. Data Parity
  8. 8. DISK MIRRORING • KEEP TO COPIES OF DATA ON TWO SEPARATE DISKS • GIVES GOOD ERROR RECOVERY • IF SOME DATA IS LOST, GET IT FROM THE OTHER SOURCE • EXPENSIVE • REQUIRES TWICE AS MANY DISKS • WRITE PERFORMANCE CAN BE SLOW • HAVE TO WRITE DATA TO TWO DIFFERENT SPOTS • READ PERFORMANCE IS ENHANCED • CAN READ DATA FROM FILE IN PARALLEL
  9. 9. DATA PARITY • WAY TO DO ERROR CHECKING AND CORRECTION • ADD UP ALL THE BITS THAT ARE 1 • IF EVEN NUMBER, SET PARITY BIT TO 0 • IF ODD NUMBER, SET PARITY BIT TO 1 • CONSIDER THE FOLLOWING 2 BYTES BYTE PARITY 10110011 1 01101010 0 • IF A SINGLE BIT IS BAD, IT IS POSSIBLE TO CORRECT IT
  10. 10. DATA STRIPING DATA STRIPING IS THE TECHNIQUE OF SEGMENTING LOGICALLY SEQUENTIAL DATA, SUCH AS A FILE, SO THAT CONSECUTIVE SEGMENTS ARE STORED ON DIFFERENT PHYSICAL STORAGE DEVICES.
  11. 11. STANDARD RAID LEVEL RAID – 0 (STRIPING) RAID – 1(MIRRORING) RAID – 2(Redundancy through Hamming code) RAID – 3(Bit Interleaved Parity) RAID – 4(Block Interleaved parity) RAID – 5(STRIPING AND PARITY) RAID-6 (P+Q redundancy)
  12. 12. RAID-0 DATA ARE STRIPPED ON ALL DISKS OFFER PERFORMANCES NO REDUNDANCY 2 DISKS MINIMUM, MAXIMUM DEPENDING OF RAID CONTROLLER DATA ARE SPLIT DEPENDING OF STRIPE SIZE (16/32/64/128KB) controller
  13. 13. RAID-1 DATA MIRRORED (DUPLICATED) ON SECOND HARD DISK OFFER REDUNDANCY EQUIVALENT OF ONE DISK SPACE LOST FOR REDUNDANCY ONLY ON 2 DISKS SUPPORT ONE DISK FAILURE Controller
  14. 14. • STRIPES DATA AT THE BIT LEVEL • USES A HAMMING CODE FOR ERROR CORRECTION. • THE DISKS ARE SYNCHRONIZED BY THE CONTROLLER TO SPIN AT THE SAME ANGULAR ORIENTATION • EXTREMELY HIGH DATA TRANSFER RATES ARE POSSIBLE. • THIS IS THE ONLY ORIGINAL LEVEL OF RAID THAT IS NOT CURRENTLY USED. RAID-2
  15. 15. RAID-3  RAID 3 IS CONFIGURED WITH AT LEAST THREE DRIVES  TWO DRIVES CARRY THE DATA AND THE THIRD DRIVE CARRIES PARITY INFORMATION.  USES BYTE-LEVEL STRIPING WITH A DEDICATED PARITY DISK.  GENERALLY CANNOT SERVICE MULTIPLE REQUESTS SIMULTANEOUSLY.  ANY I/O OPERATION REQUIRES ACTIVITY ON EVERY DISK AND USUALLY REQUIRES SYNCHRONIZED SPINDLES
  16. 16. RAID-4 A RAID 4 USES BLOCK-LEVEL STRIPING WITH A DEDICATED PARITY DISK. OTHER ARE SAME AS RAID 3
  17. 17.  Stripes data and parity to generate redundancy.  The parity is distributed through the stripe of the disk array.  both parity and data are striped across a set of separate disks.  Data chunks are much larger than the average I/O size, but are still resizable.  Disks are able to satisfy requests independently RAID-5
  18. 18. RAID-6  Data is striped across all disks (minimum of four)  A two parity blocks for each data block (p and q in the diagram) is written on the same stripe.  If one physical disk fails, the data from the failed disk can be rebuilt onto a replacement disk.  Provides for faster rebuilding of data from a failed disk.
  19. 19. NESTED RAID LEVEL LEVELS OF NESTED RAID, ALSO KNOWN AS HYBRID RAID COMBINE TWO OR MORE OF THE STANDARD LEVELS OF RAID TO GAIN PERFORMANCE, ADDITIONAL REDUNDANCY, OR BOTH.
  20. 20. Nested Raid Level RAID- (0+1) RAID-10 RAID-50 RAID-60
  21. 21. RAID (0+1) • RAID-01 IS TECHNICALLY A COMBINATION OF RAID-1 AND RAID-0, INCLUDES BOTH MIRRORING AND STRIPING, BUT WITHOUT PARITY.
  22. 22. RAID 10 IT USES RAID-1MIRRORING AND RAID-0 STRIPING, AND HAS BOTH SECURITY AND SEQUENTIAL PERFORMANCE. IT IS A STRIPED RAID-0 ARRAY WHOSE SEGMENTS ARE MIRRORED RAID-1. IT IS SIMILAR IN PERFORMANCE TO RAID 0+1, BUT WITH BETTER FAULT TOLERANCE AND REBUILD PERFORMANCE. IT HAS THE SAME FAULT TOLERANCE AS RAID-1 WITH THE SAME OVERHEAD FOR FAULT TOLERANCE AS MIRRORING ALONE.
  23. 23. RAID-50 • COMBINES MULTIPLE RAID 5 SETS WITH RAID 0 (STRIPING). • REBUILD TIMES ARE SUBSTANTIALLY LESS THAN A SINGLE LARGE RAID 5 ARRAY. • USABLE CAPACITY OF RAID 50 IS BETWEEN 67% - 94%, DEPENDING ON THE NUMBER OF DATA DRIVES IN THE RAID SET.
  24. 24. RAID-60 • COMBINES MULTIPLE RAID 6 SETS WITH RAID 0 (STRIPING). • DUAL PARITY ALLOWS THE FAILURE OF TWO DISKS IN EACH RAID 6 ARRAY. • STRIPING HELPS TO INCREASE CAPACITY AND PERFORMANCE WITHOUT ADDING DISKS TO EACH RAID 6 ARRAY .
  25. 25. IMPLEMENTATION OF RAID • THERE ARE TOW TYPES OF RAID IMPLEMENTATION. Software Implementation Hardware Implementation
  26. 26. SOFTWARE IMPLEMENTATION • SOFTWARE RAID CAN BE IMPLEMENTED IN A VARIETY OF WAYS: IN THIS CASE, THE RAID IMPLEMENTATION IS AN APPLICATION RUNNING ON THE HOST WITHOUT ANY ADDITIONAL HARDWARE. THIS TYPE OF SOFTWARE RAID USES HARD DISK DRIVES WHICH ARE ATTACHED TO THE COMPUTER SYSTEM VIA A BUILT-IN I/O INTERFACE OR A PROCESSOR-LESS HOST BUS ADAPTER (HBA). THE RAID BECOMES ACTIVE AS SOON AS THE OPERATING SYSTEM HAS LOADED THE RAID DRIVER SOFTWARE.
  27. 27. SOFTWARE IMPLEMENTATION SOFTWARE BASED RAID: • SOFTWARE IMPLEMENTATIONS ARE PROVIDED BY MANY OPERATING SYSTEMS. • A SOFTWARE LAYER SITS ABOVE THE DISK DEVICE DRIVERS AND PROVIDES AN ABSTRACTION LAYER BETWEEN THE LOGICAL DRIVES(RAIDS) AND PHYSICAL DRIVES. • SERVER'S PROCESSOR IS USED TO RUN THE RAID SOFTWARE. • USED FOR SIMPLER CONFIGURATIONS LIKE RAID0 AND RAID1.
  28. 28. HARDWARE IMPLEMENTATION • A HARDWARE RAID SOLUTION HAS ITS OWN PROCESSOR AND MEMORY TO RUN THE RAID APPLICATION. IN THIS IMPLEMENTATION, THE RAID SYSTEM IS AN INDEPENDENT SMALL COMPUTER SYSTEM DEDICATED TO THE RAID APPLICATION, OFFLOADING THIS TASK FROM THE HOST SYSTEM. HARDWARE RAID CAN BE FOUND AS AN INTEGRAL PART OF THE SOLUTION
  29. 29. HARDWARE IMPLEMENTATION HARDWARE BASED RAID: • A HARDWARE IMPLEMENTATION OF RAID REQUIRES AT LEAST A SPECIAL- PURPOSE RAID CONTROLLER. • ON A DESKTOP SYSTEM THIS MAY BE BUILT INTO THE MOTHERBOARD. • PROCESSOR IS NOT USED FOR RAID CALCULATIONS AS A SEPARATE CONTROLLER PRESENT.
  30. 30. • The key to performance increases under RAID is parallelism. The ability to access multiple disks simultaneously allows for data to be written to or read from a RAID array faster than would be possible with a single drive. Performance Issue can be discussed by four points: • Read and Write Performance • Positioning and Transfer Performance • Stripe Width and Stripe Size RAID Performance Issue
  31. 31. • Mirroring: In Raid every piece of data is duplicated, stored on both drives. There's absolutely no reason to access both drives; the controller, if intelligently programmed, will only ask one of the drives for the data--the other drive can be used to satisfy a different request. This makes RAID significantly faster than a single drive for reads, under most conditions. • Striping Without Parity: A RAID 0 array has about equal read and write performance . The reason is that the "chopping up" of the data without parity calculation means we must access the same number of drives for reads as we do for writes. • Striping With Parity: As with mirroring, write performance when striping with parity (RAID levels 3 through 6) is worse than read performance, but unlike mirroring, the "hit" taken on a write when doing striping with parity is much more significant. Read and Write Performance
  32. 32. • Mirroring: Mirroring improves positioning performance. However, once the data is found, it will be read off one drive. • Striping: Large files that are split into enough blocks to span every drive in the array require each drive to position to a particular spot, so positioning performance is not improved; once the heads are all in place however, data is read from all the drives at once, greatly improving transfer performance. On reads, small files that don't require reading from all the disks in the array can allow a smart controller to actually run two or more accesses in parallel. This improves both positioning and transfer performance. Positioning and Transfer Performance
  33. 33. • Decreasing Stripe Size: As stripe size is decreased, files are broken into smaller and smaller pieces. This increases the number of drives that an average file will use to hold all the blocks containing the data of that file, theoretically increasing transfer performance, but decreasing positioning performance. • Increasing Stripe Size: Increasing the stripe size of the array does the opposite of decreasing it, of course. Fewer drives are required to store files of a given size, so transfer performance decreases. However, if the controller is optimized to allow it, the requirement for fewer drives allows the drives not needed for a particular access to be used for another one, improving positioning performance. Stripe Size
  34. 34. Performance and Advantages Comparison among RAID Levels
  35. 35. RAID has been with us for about 20 years, but until only recently it was the domain of big systems and deep pockets. During those 20 years, however, a number of factors have come together to make RAID a reality for both big servers and common desktop systems. Imagine a world where dirt-cheap RAID on every computer means no one ever again losing critical data. The first desktop RAID systems have already appeared on the market. As disk size and cost continue to decline, widespread use of RAID on the desktop is only a matter of time. Conclusion
  36. 36. • 1. RAID for Enterprise Computing – Copyright @ VERITAS Software Corporation, 1999, 2000 • 2. RAID: High-Performance, Reliable Secondary Storage- • 3. http://en.wikipedia.org/wiki/RAID • 4. http://en.wikipedia.org/wiki/Non- standard_RAID_levels#RAID_5E.2C_RAID_5EE.2C_and_RAID_6E • 5. http://en.wikipedia.org/wiki/Standard_RAID_levels • 6. http://en.wikipedia.org/wiki/Nested_RAID_levels • 7. http://www.pcguide.com/ • 8. RAID Levels and Components Explained-Developed in Nov. 2007 by Jerry Scott • 9. RAID Storage — Speed and Security (PDF) • 10. RAID Theory: An Overview - Ben Rockwood, Cuddletech • 11. Storage solutions white paper - Copyright 2006 Adaptec, Inc. References

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