iostat.tproj/iostat.8

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   2 .\" Copyright (c) 1997 Kenneth D. Merry.
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  28 .\" $FreeBSD: src/usr.sbin/iostat/iostat.8,v 1.20 2001/08/07 13:59:48 ru Exp $
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  61 .\"     @(#)iostat.8    8.1 (Berkeley) 6/6/93
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  63 .Dd September 27, 2001
  64 .Dt IOSTAT 8
  65 .Os
  66 .Sh NAME
  67 .Nm iostat
  68 .Nd report
  69 .Tn I/O
  70 statistics
  71 .Sh SYNOPSIS
  72 .Nm
  73 .Op Fl CdKIoT?\&
  74 .Op Fl c Ar count
  75 .Op Fl n Ar devs
  76 .Op Fl w Ar wait
  77 .Op Ar drives
  78 .Sh DESCRIPTION
  79 .Nm Iostat
  80 displays kernel
  81 .Tn I/O
  82 statistics on terminal, device and cpu operations.
  83 The first statistics that are printed are averaged over the system uptime.
  84 To get information about the current activity, a suitable wait time should
  85 be specified, so that the subsequent sets of printed statistics will be
  86 averaged over that time.
  87 .Pp
  88 The options are as follows:
  89 .Bl -tag -width flag
  90 .It Fl c
  91 Repeat the display
  92 .Ar count
  93 times.
  94 If no
  95 .Ar wait
  96 interval is specified, the default is 1 second.
  97 .It Fl C
  98 Display CPU statistics.
  99 This is on by default, unless
 100 .Fl d
 101 is specified.
 102 .It Fl d
 103 Display only device statistics.
 104 If this flag is turned on, only device statistics will be displayed, unless
 105 .Fl C
 106 or
 107 .Fl T
 108 is also specfied to enable the display of CPU or TTY statistics.
 109 .It Fl I
 110 Display total statstics for a given time period, rather than average
 111 statistics for each second during that time period.
 112 .It Fl K
 113 In the blocks transferred display (-o), display block count in kilobytes rather
 114 then the device native block size.
 115 .It Fl n
 116 Display up to
 117 .Ar devs
 118 number of devices.
 119 .Nm
 120 will display fewer devices if there aren't
 121 .Ar devs
 122 devices present.
 123 .It Fl o
 124 Display old-style
 125 .Nm
 126 device statistics.
 127 Sectors per second, transfers per second, and miliseconds per seek are
 128 displayed.
 129 If
 130 .Fl I
 131 is specified, total blocks/sectors, total transfers, and
 132 miliseconds per seek are displayed.
 133 .It Fl T
 134 Display TTY statistics.
 135 This is on by default, unless
 136 .Fl d
 137 is specified.
 138 .It Fl w
 139 Pause
 140 .Ar wait
 141 seconds between each display.
 142 If no repeat
 143 .Ar count
 144 is specified, the default is infinity.
 145 .It Fl ?\&
 146 Display a usage statement and exit.
 147 .El
 148 .Pp
 149 .Nm Iostat
 150 displays its information in the following format:
 151 .Bl -tag -width flag
 152 .It tty
 153 .Bl -tag -width indent -compact
 154 .It tin
 155 characters read from terminals
 156 .It tout
 157 characters written to terminals
 158 .El
 159 .It devices
 160 Device operations.
 161 The header of the field is the device name and unit number.
 162 .Nm
 163 will display as many devices as will fit in a standard 80 column screen, or
 164 the maximum number of devices in the system, whichever is smaller.
 165 If
 166 .Fl n
 167 is specified on the command line,
 168 .Nm
 169 will display the smaller of the
 170 requested number of devices, and the maximum number of devices in the system.
 171 To force
 172 .Nm
 173 to display specific drives, their names may be supplied on the command
 174 line.
 175 .Nm
 176 will not display more devices than will fit in an 80 column screen, unless
 177 the
 178 .Fl n
 179 argument is given on the command line to specify a maximum number of
 180 devices to display, or the list of specified devices exceeds 80 columns.
 181 If fewer devices are specified on the command line than will fit in an 80
 182 column screen,
 183 .Nm
 184 will show only the specified devices.
 185 .Pp
 186 The standard
 187 .Nm
 188 device display shows the following statistics:
 189 .Pp
 190 .Bl -tag -width indent -compact
 191 .It KB/t
 192 kilobytes per transfer
 193 .It tps
 194 transfers per second
 195 .It MB/s
 196 megabytes per second
 197 .El
 198 .Pp
 199 The standard
 200 .Nm
 201 device display, with the
 202 .Fl I
 203 flag specified, shows the following statistics:
 204 .Pp
 205 .Bl -tag -width indent -compact
 206 .It KB/t
 207 kilobytes per transfer
 208 .It xfrs
 209 total number of transfers
 210 .It MB
 211 total number of megabytes transferred
 212 .El
 213 .Pp
 214 The old-style
 215 .Nm
 216 display (using
 217 .Fl o )
 218 shows the following statistics:
 219 .Pp
 220 .Bl -tag -width indent -compact
 221 .It sps
 222 sectors transferred per second
 223 .It tps
 224 transfers per second
 225 .It msps
 226 average milliseconds per transaction
 227 .El
 228 .Pp
 229 The old-style
 230 .Nm
 231 display, with the
 232 .Fl I
 233 flag specified, shows the following statistics:
 234 .Pp
 235 .Bl -tag -width indent -compact
 236 .It blk
 237 total blocks/sectors transferred
 238 .It xfr
 239 total transfers
 240 .It msps
 241 average milliseconds per transaction
 242 .El
 243 .It cpu
 244 .Bl -tag -width indent -compact
 245 .It \&us
 246 % of cpu time in user mode
 247 .It \&sy
 248 % of cpu time in system mode
 249 .It \&id
 250 % of cpu time in idle mode
 251 .El
 252 .El
 253 .Sh EXAMPLES
 254 .Dl iostat -w 1 disk0 disk2
 255 .Pp
 256 Display statistics for the first and third disk devices device every
 257 second ad infinitum.
 258 .Pp
 259 .Dl iostat -c 2
 260 .Pp
 261 Display the statistics for the first four devices in the system twice, with
 262 a one second display interval.
 263 .Pp
 264 .Dl iostat -Iw 3
 265 .Pp
 266 Display total statistics every three seconds ad infinitum.
 267 .Pp
 268 .Dl iostat -odICTw 2 -c 9
 269 .Pp
 270 Display total statistics using the old-style output format 9 times, with
 271 a two second interval between each measurement/display.
 272 The
 273 .Fl d
 274 flag generally disables the TTY and CPU displays, but since the
 275 .Fl T
 276 and
 277 .Fl C
 278 flags are given, the TTY and CPU displays will be displayed.
 279 .Sh SEE ALSO
 280 .Xr fstat 1 ,
 281 .Xr netstat 1 ,
 282 .Xr nfsstat 1 ,
 283 .Xr ps 1 ,
 284 .Xr pstat 8 ,
 285 .Pp
 286 The sections starting with ``Interpreting system activity'' in
 287 .%T "Installing and Operating 4.3BSD" .
 288 .Sh HISTORY
 289 This version of
 290 .Nm
 291 first appeared in
 292 .Nm FreeBSD 3.0 .