1 The following is a demonstration of the iopattern program, 2 3 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 6 disk activity, 7 8 # iopattern 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 17 ^C 18 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 21 average event size. 22 23 24 25 The following demonstrates iopattern while running a "find" command to 26 cause random disk activity, 27 28 # iopattern 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 38 ^C 39 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. 43 44 45 46 iopattern has options. Here we print timestamps "-v" and measure every 10 47 seconds, 48 49 # iopattern -v 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 56 ^C 57 58
Indexes created Wed Apr 22 00:22:44 UTC 2026