Dell PowerVault MD3000i - Manual (Page 3)

Dell™ PowerVault MD3000 and MD3000i Array Tuning Best Practices
December 2008 – Revision A01 Page 3
Table of Contents
1 AUDIENCE AND SCOPE .............................................................................................................................. 4
2 PERFORMANCE TUNING OVERVIEW .......................................................................................................... 4
2.1 C OMPONENTS T HAT I NFLUENCE S TORAGE P ERFORMANCE ...........................................................................................4
2.2 B ASIC A PPROACH TO P ERFORMANCE T UNING ............................................................................................................4
3 APPLICATION SOFTWARE CONSIDERATIONS.............................................................................................. 5
4 CONFIGURING THE MD3000/MD3000I ...................................................................................................... 6
4.1 D ETERMINING THE B EST R AID L EVEL ........................................................................................................................6
4.1.1 Selecting a RAID Level ‐ High Write Mix Scenario ..................................................................................8
4.1.2 Selecting a RAID Level ‐ Low Write Mix Scenario...................................................................................8
4.2 C HOOSING THE N UMBER OF D RIVES IN A D ISK G ROUP .................................................................................................8
4.3 V IRTUAL D ISK L OCATION AND C APACITY ...................................................................................................................9
4.4 V IRTUAL D ISK O WNERSHIP ...................................................................................................................................10
4.5 C ALCULATING O PTIMAL S EGMENT AND S TRIPE S IZE ..................................................................................................10
4.6 C ACHE S ETTINGS ................................................................................................................................................12
4.6.1 Setting the Virtual Disk‐Specific Write Cache and Write Cache Mirroring...........................................12
4.6.2 Setting the Virtual Disk‐Specific Read Cache Pre‐fetch........................................................................12
4.6.3 Setting the Storage Array Cache Block Size .........................................................................................13
4.7 T UNING U SING A RRAY P ERFORMANCE D ATA ...........................................................................................................14
4.7.1 Collecting Performance Statistics ........................................................................................................14
4.7.2 RAID Level ............................................................................................................................................14
4.7.3 I/O Distribution ....................................................................................................................................15
4.7.4 Stripe Size.............................................................................................................................................16
4.7.5 Write Algorithm Data ..........................................................................................................................19
4.8 U SING THE CLI P ERFORMANCE M ONITOR ...............................................................................................................21
4.9 O THER A RRAY C ONSIDERATIONS ...........................................................................................................................22
4.9.1 Global Media Scan Rate.......................................................................................................................22
4.9.2 Setting the Virtual Disk‐Specific Media Scan .......................................................................................22
4.10 P REMIUM F EATURE P ERFORMANCE ..................................................................................................................22
4.10.1 Getting Optimal Performance from Snapshot.................................................................................22
4.10.2 Getting Optimal Performance from Virtual Disk Copy ....................................................................22
5 CONSIDERING THE HOST SERVER(S)..........................................................................................................23
5.1 H OST H ARDWARE P LATFORM ...............................................................................................................................23
5.1.1 Considering the Server Hardware Architecture....................................................................................23
5.1.2 Sharing Bandwidth on the Dell™ MD3000i with Multiple NICs ...........................................................23
5.1.3 Sharing Bandwidth with Multiple SAS HBAs ........................................................................................24
5.2 C ONSIDERING THE S YSTEM S OFTWARE ...................................................................................................................25
5.2.1 Buffering the I/O ..................................................................................................................................25
5.2.2 Aligning Host I/O with RAID Striping....................................................................................................25
APPENDIX A: OBTAINING ADDITIONAL PERFORMANCE TOOLS ..........................................................................27
APPENDIX B: SYSTEM TROUBLESHOOTING .......................................................................................................28
APPENDIX C: REFERENCES ................................................................................................................................29
APPENDIX D: GLOSSARY OF TERMS ...................................................................................................................30