Performance Evaluation of RAID6 Yan Li, Roland Ibbett, Nigel Topham - - PowerPoint PPT Presentation

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Performance Evaluation of RAID6 Yan Li, Roland Ibbett, Nigel Topham - - PowerPoint PPT Presentation

Aug 30, 2022 133 likes •255 views

V I N E U R S E I H T Y T O H F G R E U D B I N Performance Evaluation of RAID6 Yan Li, Roland Ibbett, Nigel Topham and Tim Courtney School of Informatics University of Edinburgh Xyratex, UK Yan Li Performance

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SLIDE 1

T H E U N I V E R S I T Y O F E D I N B U R G H

Performance Evaluation of RAID6

Yan Li, Roland Ibbett, Nigel Topham and Tim Courtney‡ School of Informatics University of Edinburgh

‡Xyratex, UK Yan Li Performance Evaluation of RAID6 Y.Li-24@sms.ed.ac.uk

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SLIDE 2

Project Motivation 1

T H E U N I V E R S I T Y O F E D I N B U R G H

Project Motivation

  • Increasing the number of disks results in higher disk failure possibility.
  • The larger disk capacity leads to a longer rebuilding time, resulting higher bit

error possibility during the reconstruction.

  • The end-of-life issue.
  • Double disk failure protection scheme RAID6 is becoming more and more

necessary.

Yan Li Performance Evaluation of RAID6 Y.Li-24@sms.ed.ac.uk

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SLIDE 3

Project Motivation 2

T H E U N I V E R S I T Y O F E D I N B U R G H

Reliability of systems over 5 years old

80 100 120 140 160 180 200 1 1.5 2 2.5 3 3.5 x 10

5

number of disks MTTFof RAID systems (Hours) 80 100 120 140 0.02 0.03 0.04 0.05 0.06 0.07 number of disks annual system failure rate 80 100 120 140 160 180 200 2 4 6 x 10

7

number of disks MTTF of RAID systems (Hours) 80 100 120 140 1 1.5 2 2.5 3 x 10

−4

numbre of disks annual system failure rate RAID6 RAID6 RAID5 RAID5 RAID5 MTTF of disks = 1000,000/30, MTTR = 8 hours

Yan Li Performance Evaluation of RAID6 Y.Li-24@sms.ed.ac.uk

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SLIDE 4

Project Motivation 3

T H E U N I V E R S I T Y O F E D I N B U R G H

Project Goal

  • Evaluate the performance of RAID6 under the SPC Benchmark-1 (SPC-1)

workload through simulation and explore the design space. – The performance of RAID6 under fault-free operation. – The performance of degraded mode. – Find out how to allocate resources between rebuilding and serving of incoming requests during the rebuilding stage so that it needs the shortest time for the system to return to normal operation mode

Yan Li Performance Evaluation of RAID6 Y.Li-24@sms.ed.ac.uk

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SLIDE 5

Performance of RAID6 4

T H E U N I V E R S I T Y O F E D I N B U R G H

Performance of RAID6

  • We focus on the RAID6 algorithms that store the redundant information

separately from the data in each stripe, like Read-Solomon, EVENODD and

  • RDP. 8+P+Q data layout is used.
  • Effect of RAID controller processing time.
  • Optimum size of the stripe unit under SPC-1 workload
  • The effect of increasing cache size and number of disks and their interactive

effects.

Yan Li Performance Evaluation of RAID6 Y.Li-24@sms.ed.ac.uk

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SLIDE 6

Simulation Results 5

T H E U N I V E R S I T Y O F E D I N B U R G H

Effect of RAID controller processing time

50 100 150 200 250 300 350 25 30 35 40 45 50 55 60 Controller Processing Time (us) Max SPC−1 BSU for 30ms response 28Disks 14Disks

Yan Li Performance Evaluation of RAID6 Y.Li-24@sms.ed.ac.uk

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SLIDE 7

Simulation Results 6

T H E U N I V E R S I T Y O F E D I N B U R G H

Optimum Size of Stripe Unit without Cache

Yan Li Performance Evaluation of RAID6 Y.Li-24@sms.ed.ac.uk

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SLIDE 8

Simulation Results 7

T H E U N I V E R S I T Y O F E D I N B U R G H

Optimum Size of Stripe Unit with Cache

Yan Li Performance Evaluation of RAID6 Y.Li-24@sms.ed.ac.uk

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SLIDE 9

Simulation Results 8

T H E U N I V E R S I T Y O F E D I N B U R G H

Effect of Cache Size

0.2 0.4 0.6 0.8 1 20 30 40 50 60 70 80 90 cache size/total ASU capacity (%) Max SPC−1 BSU for 30ms response RAID5 RAID6 0.2 0.4 0.6 0.8 1 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1 cache size/total ASU capacity read miss rate RAID5 RAID6

Yan Li Performance Evaluation of RAID6 Y.Li-24@sms.ed.ac.uk

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SLIDE 10

Performance of RAID6 9

T H E U N I V E R S I T Y O F E D I N B U R G H

Summary

  • The achievable maximum SPC-1 BSU number of RAID6 is mainly decide by

the disk array. The controller processing time has little effect on that.

  • Among the tested value (4, 8, 16, 32, 64 kBytes), the optimum size of stripe

unit for RAID6 without cache is 16 KBytes; and that of RAID6 system with cache is 32 KBytes. This is irrelevant to the number of disks in the system.

  • With cache that is 0.12% of the total asu capacity, there is about 100%

increase on the performance.

  • With the same size of cache and asu capacity, the performance of RAID6 is

about 70% of RAID5 under SPC-1 workload.

Yan Li Performance Evaluation of RAID6 Y.Li-24@sms.ed.ac.uk

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SLIDE 11

Future Work 10

T H E U N I V E R S I T Y O F E D I N B U R G H

Future Work

  • Test the effect of controller processing time with larger disk arrays
  • Study the performance of RAID6 under degraded mode.
  • The performance of RAID6 under other workload.
  • Investigate the best recovering scheme.

Yan Li Performance Evaluation of RAID6 Y.Li-24@sms.ed.ac.uk