They don't look that off to me. However, try testing with higher QDs (i.e. Simultaneous I/O threads), try for example 3 and 32 (those are what we use for random write testing).
Thanks, Hellhammer. Here are my results for 3 and 32 threads, 4K random, respectively. Are they okay?
DiskTester 2.2 64-bit, diglloydTools 2.2.0, 2012-12-15 18:05
OS X 10.6.8, 8 CPU cores, 8192MB memory
Capacity GB: 466.07
Free space GB: 261.29
Simultaneous I/O threads: 3
Transfer size per I/O: 4K
Number of transfers (per thread): 131072
Test file size per thread: 32GB
Gap size (spacing): 0B
Total space required: 96GB
Aggregate I/O size: 1.50GB
File system unified buffer cache: DISABLED (default)
Test type: RANDOM
Writing 3 simultaneous streams...
Code:
MB Write MB/sec Write ops/sec
53 9.0 2295.0
77 6.5 1664.1
96 5.4 1373.4
112 4.7 1197.2
125 4.2 1071.9
137 3.8 978.6
148 3.5 905.5
158 3.3 846.3
167 3.1 796.5
176 2.9 753.3
184 2.8 717.0
192 2.7 683.1
198 2.6 653.2
205 2.5 627.9
212 2.4 605.0
218 2.3 584.2
224 2.2 564.7
230 2.1 546.0
236 2.1 530.4
241 2.0 516.2
247 2.0 502.9
252 1.9 490.6
[...]
1533 0.4 97.8
1535 0.4 97.8
1536 0.4 97.8
Reading 3 simultaneous streams...
Code:
MB Read MB/sec Read ops/sec
3 0.6 141.1
6 0.5 137.2
9 0.5 139.8
13 0.5 140.5
16 0.6 141.0
19 0.5 139.7
22 0.5 139.2
25 0.5 138.2
28 0.5 136.9
31 0.5 136.1
34 0.5 135.6
38 0.5 135.4
41 0.5 135.3
44 0.5 134.4
46 0.5 133.5
49 0.5 133.2
[...]
1530 0.5 130.1
1533 0.5 130.1
1536 0.5 130.1
Simultaneous I/O threads: 32
Transfer size per I/O: 4K
Number of transfers (per thread): 4096
Test file size per thread: 1GB
Gap size (spacing): 0B
Total space required: 32GB
Aggregate I/O size: 512MB
Test type: RANDOM
Writing 32 simultaneous streams...
Code:
MB Write MB/sec Write ops/sec
59 0.9 240.1
88 0.7 177.6
110 0.6 147.9
129 0.5 129.4
145 0.5 116.5
160 0.4 107.0
174 0.4 99.6
187 0.4 93.8
200 0.3 89.1
212 0.3 85.0
224 0.3 81.5
235 0.3 78.6
246 0.3 76.0
[...]
497 0.2 53.8
508 0.2 53.5
512 0.2 53.4
Reading 32 simultaneous streams...
Code:
MB Read MB/sec Read ops/sec
13 0.2 55.8
27 0.2 55.4
41 0.2 55.5
55 0.2 55.7
69 0.2 55.7
83 0.2 55.7
97 0.2 55.6
111 0.2 55.6
124 0.2 55.6
138 0.2 55.5
151 0.2 55.2
165 0.2 55.1
178 0.2 55.1
192 0.2 55.1
206 0.2 55.0
220 0.2 55.0
233 0.2 54.9
246 0.2 54.8
[...]
479 0.2 53.3
491 0.2 53.1
502 0.2 52.9
512 0.2 52.9
Write 512MB in seconds: 76.7
Read 512MB in seconds: 77.4
Aggregate write rate MB/sec: 6.7
Aggregate read rate MB/sec: 6.6
Write ops/sec: 1709
Read ops/sec: 1692