Commit | Line | Data |
---|---|---|
ab7d1648 KT |
1 | .TH IOSTAT 1M |
2 | .SH NAME | |
3 | iostat \- report I/O statistics | |
4 | .SH SYNOPSIS | |
5 | .B iostat | |
6 | [ option ] ... | |
7 | [ interval [ count ] ] | |
8 | .SH DESCRIPTION | |
9 | .I Iostat | |
10 | delves into the system and reports certain statistics kept about | |
11 | input-output activity. | |
12 | Information is kept about up to three different disks | |
13 | (RF, RK, RP) and about typewriters. | |
14 | For each disk, IO completions and number of words transferred | |
15 | are counted; for typewriters collectively, the number | |
16 | of input and output characters are counted. | |
17 | Also, each sixtieth of a second, | |
18 | the state of each disk is examined | |
19 | and a tally is made if the disk is active. | |
20 | The tally goes into | |
21 | one of four categories, depending on whether the system is | |
22 | executing in user mode, in `nice' (background) | |
23 | user mode, in system mode, or idle. | |
24 | From all these numbers and from the known transfer rates | |
25 | of the devices it is possible to determine | |
26 | information such as the degree of IO overlap | |
27 | and average seek times for each device. | |
28 | .PP | |
29 | The optional | |
30 | .I interval | |
31 | argument causes | |
32 | .I iostat | |
33 | to report once each | |
34 | .I interval | |
35 | seconds. | |
36 | The first report is for all time since a reboot and each | |
37 | subsequent report is for the last interval only. | |
38 | .PP | |
39 | The optional | |
40 | .I count | |
41 | argument restricts the number of reports. | |
42 | .PP | |
43 | With no option argument | |
44 | .I iostat | |
45 | reports for each disk the number of transfers per minute, | |
46 | the milliseconds | |
47 | per average seek, | |
48 | and the milliseconds per data transfer exclusive of seek time. | |
49 | It also gives the percentage of time the system has | |
50 | spend in each of the four categories mentioned above. | |
51 | .PP | |
52 | The following options are available: | |
53 | .TP | |
54 | .B \-t | |
55 | Report the number of characters of terminal IO per second as well. | |
56 | .TP | |
57 | .B \-i | |
58 | Report the percentage of time spend in each | |
59 | of the four categories mentioned above, | |
60 | the percentage of time each disk was active (seeking or transferring), | |
61 | the percentage of time any disk was active, | |
62 | and the percentage of time spent in `IO wait:' | |
63 | idle, but with a disk active. | |
64 | .TP | |
65 | .B \-s | |
66 | Report the raw timing information: 32 numbers indicating | |
67 | the percentage of time spent in each of the possible | |
68 | configurations of 4 system states and 8 IO states | |
69 | (3 disks each active or not). | |
70 | .TP | |
71 | .B \-b | |
72 | Report on the usage of IO buffers. | |
73 | .SH FILES | |
74 | /dev/mem, /unix |