Dell PowerVault MD3000i Dell PowerVault MD3000/MD3000i Array Tuning Best Pract - Page 3

Dell™ PowerVault MD3000 and MD3000i Array Tuning Best Practices Table of Contents 1 AUDIENCE AND SCOPE ...4 2 PERFORMANCE TUNING OVERVIEW ...4 2.1 COMPONENTS THAT INFLUENCE STORAGE PERFORMANCE 4 2.2 BASIC APPROACH TO PERFORMANCE TUNING ...4 3 APPLICATION SOFTWARE CONSIDERATIONS 5 4 CONFIGURING THE MD3000/MD3000I ...6 4.1 DETERMINING THE BEST RAID LEVEL ...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 CHOOSING THE NUMBER OF DRIVES IN A DISK GROUP 8 4.3 VIRTUAL DISK LOCATION AND CAPACITY ...9 4.4 VIRTUAL DISK OWNERSHIP...10 4.5 CALCULATING OPTIMAL SEGMENT AND STRIPE SIZE 10 4.6 CACHE SETTINGS ...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 TUNING USING ARRAY PERFORMANCE DATA...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 USING THE CLI PERFORMANCE MONITOR ...21 4.9 OTHER ARRAY CONSIDERATIONS ...22 4.9.1 Global Media Scan Rate...22 4.9.2 Setting the Virtual Disk‐Specific Media Scan 22 4.10 PREMIUM FEATURE PERFORMANCE ...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 HOST HARDWARE PLATFORM ...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 CONSIDERING THE SYSTEM SOFTWARE ...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 December 2008 - Revision A01 Page 3