1.\" Copyright (c) 1985, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" %sccs.include.redist.roff% 5.\" 6.\" @(#)iostat.8 8.1 (Berkeley) 06/06/93 7.\" 8.Dd 9.Dt IOSTAT 8 10.Os BSD 4 11.Sh NAME 12.Nm iostat 13.Nd report 14.Tn I/O 15statistics 16.Sh SYNOPSIS 17.Nm iostat 18.Op Fl c Ar count 19.Op Fl M Ar core 20.Op Fl N Ar system 21.Op Fl w Ar wait 22.Op Ar drives 23.Sh DESCRIPTION 24.Nm Iostat 25displays kernel 26.Tn I/O 27statistics on terminal, disk and cpu 28operations. 29.Pp 30The options are as follows: 31.Bl -tag -width flag 32.It Fl c 33Repeat the display 34.Ar count 35times. 36The first display is for the time since a reboot and each subsequent 37report is for the time period since the last display. 38If no 39.Ar wait 40interval is specified, the default is 1 second. 41.It Fl M 42Extract values associated with the name list from the specified core 43instead of the default 44.Dq Pa /dev/kmem . 45.It Fl N 46Extract the name list from the specified system instead of the default 47.Dq Pa /vmunix . 48.It Fl w 49Pause 50.Ar wait 51seconds between each display. 52If no repeat 53.Ar count 54is specified, the default is infinity. 55.El 56.Pp 57.Nm Iostat 58displays its information in the following format: 59.Bl -tag -width flag 60.It tty 61.Bl -tag -width indent -compact 62.It tin 63characters read from terminals 64.It tout 65characters written to terminals 66.El 67.It disks 68Disk operations (this field is system dependent). 69The header of the field is the disk name and unit number. 70If more than four disk drives are configured in the system, 71.Nm iostat 72displays only the first four drives. 73To force 74.Nm iostat 75to display specific drives, their names may be supplied on the command 76line. 77.Pp 78.Bl -tag -width indent -compact 79.It sps 80sectors transferred per second 81.It tps 82transfers per second 83.It msps 84milliseconds per average seek (including implied 85seeks and rotational latency) 86.El 87.It cpu 88.Bl -tag -width indent -compact 89.It \&us 90% of cpu time in user mode 91.It \&ni 92% of cpu time in user mode running niced processes 93.It \&sy 94% of cpu time in system mode 95.It \&id 96% of cpu time in idle mode 97.El 98.El 99.Sh FILES 100.Bl -tag -width /dev/kmem -compact 101.It Pa /vmunix 102Default kernel namelist. 103.It Pa /dev/kmem 104Default memory file. 105.El 106.Sh SEE ALSO 107.Xr fstat 1 , 108.Xr netstat 1 , 109.Xr nfsstat 1 , 110.Xr \&ps 1 , 111.Xr systat 1 , 112.Xr vmstat 1 , 113.Xr pstat 8 114.Pp 115The sections starting with ``Interpreting system activity'' in 116.%T "Installing and Operating 4.3BSD" . 117