iostat.tproj/iostat.8

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