Dell PowerVault MD3000i Tuning Manual 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:
User Label:
Block Size:
Large IO:
Segment Size:
Stripe Size:
...
IO Statistics:
small
reads
requests 2028332119
blocks 3091968111 2518067526
avg blocks
IO pct. 93.21%
Figure 6: Second Generation Firmware - Volume Attributes Performance Stats; taken
Volume 0 Attributes:
Volume Type:
User Label:
...
BlockSize:
LargeIoSize:
...
Perf. Stats:
Reads
Writes
Large Reads
Large Writes
Total
December 2008 – Revision A01
13+1 RAID 5
MyRAID5_1
512 bytes
4096 blocks
256 blocks
3328 blocks
small
writes
147699066
4 17
6.78%
from RAID 1 volume. File: stateCaptureData.txt
RAIDVolume
MyRAID10_One
512 bytes
4096 blocks
Requests
67456452 5943724625
27283249 1144902648
0
0
94739701 7088627273
large large
reads writes
0 0 2176031185 1289775370
0 0 1315068341 4019884678
0 0
0.00% 0.00%
Blocks Avg. Blks
88
41
0 0
0 0
74
cache
total hits
0 3
0.00% 59.27%
IO Percent
71.20%
28.80%
0.00%
0.00%
100.00 %
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