1 The following is a demonstration of the iopattern program,
4 Here we run iopattern for a few seconds then hit Ctrl-C. There is a "dd"
5 command running on this system to intentionally create heavy sequential
9 %RAN %SEQ COUNT MIN MAX AVG KR KW
10 1 99 465 4096 57344 52992 23916 148
11 0 100 556 57344 57344 57344 31136 0
12 0 100 634 57344 57344 57344 35504 0
13 6 94 554 512 57344 54034 29184 49
14 0 100 489 57344 57344 57344 27384 0
15 21 79 568 4096 57344 46188 25576 44
16 4 96 431 4096 57344 56118 23620 0
19 In the above output we can see that the disk activity is mostly sequential.
20 The disks are also pulling around 30 Mb during each sample, with a large
25 The following demonstrates iopattern while running a "find" command to
26 cause random disk activity,
29 %RAN %SEQ COUNT MIN MAX AVG KR KW
30 86 14 400 1024 8192 1543 603 0
31 81 19 455 1024 8192 1606 714 0
32 89 11 469 512 8192 1854 550 299
33 83 17 463 1024 8192 1782 806 0
34 87 13 394 1024 8192 1551 597 0
35 85 15 348 512 57344 2835 808 155
36 91 9 513 512 47616 2812 570 839
37 76 24 317 512 35840 3755 562 600
40 In the above output, we can see from the percentages that the disk events
41 were mostly random. We can also see that the average event size is small -
42 which makes sense if we are reading through many directory files.
46 iopattern has options. Here we print timestamps "-v" and measure every 10
50 TIME %RAN %SEQ COUNT MIN MAX AVG KR KW
51 2005 Jul 25 20:40:55 97 3 33 512 8192 1163 8 29
52 2005 Jul 25 20:41:05 0 0 0 0 0 0 0 0
53 2005 Jul 25 20:41:15 84 16 6 512 11776 5973 22 13
54 2005 Jul 25 20:41:25 100 0 26 512 8192 1496 8 30
55 2005 Jul 25 20:41:35 0 0 0 0 0 0 0 0