Dell PowerVault MD3000i Dell PowerVault MD3000/MD3000i Array Tuning Best Pract - Page 17

Dell™ PowerVault MD3000 and MD3000i Array Tuning Best Practices In the first generation of firmware (see Figure 5), this can be determined from the 'Avg. Blocks' row which represents the average I/O block size encountered. In Generation One, the 'Large IO' field denotes a 4096 block or 2MiB size with zero registered Large Reads or Writes during the sample period. Any single host received I/O greater than the Large I/O size is broken down into chunks less than or equal to the stated Large I/O value. It is extremely rare for a host to send such large I/Os. With second generation firmware (see Figure 6), the 'Avg. Blks' column represents the average the I/O block size encountered. In Figure 6, the 'LargeIoSize' field denotes a 2MiB size with zero registered Large Reads or Writes during the sample period. Figure 5: First Generation Firmware - Stripe Size. File: stateCaptureData.txt Virtual Disk Unit 0 Configuration Volume Type: 13+1 RAID 5 User Label: MyRAID5_1 Block Size: 512 bytes Large IO: 4096 blocks Segment Size: 256 blocks Stripe Size: 3328 blocks ... IO Statistics: small small reads writes requests 2028332119 147699066 blocks 3091968111 2518067526 avg blocks 4 17 IO pct. 93.21% 6.78% large reads 0 0 0 0.00% large cache writes total hits 0 2176031185 1289775370 0 1315068341 4019884678 0 0 3 0.00% 0.00% 59.27% Figure 6: Second Generation Firmware - Volume Attributes Performance Stats; taken from RAID 1 volume. File: stateCaptureData.txt Volume 0 Attributes: Volume Type: User Label: ... BlockSize: LargeIoSize: ... Perf. Stats: Reads Writes Large Reads Large Writes Total RAIDVolume MyRAID10_One 512 bytes 4096 blocks Requests Blocks 67456452 5943724625 27283249 1144902648 0 0 0 0 94739701 7088627273 Avg. Blks 88 41 0 0 74 IO Percent 71.20% 28.80% 0.00% 0.00% 100.00 % December 2008 - Revision A01 Page 17