Dell PowerVault MD3000 - Manual (Page 17)

Dell™ PowerVault MD3000 and MD3000i Array Tuning Best Practices
December 2008 – Revision A01 Page 17
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.
Volume 0 Attributes:
Volume Type: RAIDVolume
User Label: MyRAID10_One
...
BlockSize: 512 bytes
LargeIoSize: 4096 blocks
...
Perf. Stats: Requests Blocks Avg. Blks IO Percent
Reads 67456452 5943724625 88 71.20%
Writes 27283249 1144902648 41 28.80%
Large Reads 0 0 0 0.00%
Large Writes 0 0 0 0.00%
Total 94739701 7088627273 74 100.00 %
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 large large cache
reads writes reads writes total hits
requests 2028332119 147699066 0 0 2176031185 1289775370
blocks 3091968111 2518067526 0 0 1315068341 4019884678
avg blocks 4 17 0 0 0 3
IO pct. 93.21% 6.78% 0.00% 0.00% 0.00% 59.27%
Figure 6: Second Generation Firmware - Volume Attributes Performance Stats; taken
from RAID 1 volume. File: stateCaptureData.txt
Figure 5: First Generation Firmware - Stripe Size. File: stateCaptureData.txt