1 IOSTAT(1M)                   Maintenance Commands                   IOSTAT(1M)
   2 
   3 
   4 
   5 NAME
   6        iostat - report I/O statistics
   7 
   8 SYNOPSIS
   9        /usr/bin/iostat  [-cCdDeEiImMnpPrstxXYz] [-l n] [-T u | d]
  10         [disk]... [interval [count]]
  11 
  12 
  13 DESCRIPTION
  14        The iostat utility iteratively reports terminal, disk, and tape I/O
  15        activity, as well as CPU utilization. The first line of output is for
  16        all time since boot; each subsequent line is for the prior interval
  17        only.
  18 
  19 
  20        To compute this information, the kernel maintains a number of counters.
  21        For each disk, the kernel counts reads, writes, bytes read, and bytes
  22        written. The kernel also takes hi-res time stamps at queue entry and
  23        exit points, which allows it to keep track of the residence time and
  24        cumulative residence-length product for each queue. Using these values,
  25        iostat produces highly accurate measures of throughput, utilization,
  26        queue lengths, transaction rates and service time. For terminals
  27        collectively, the kernel simply counts the number of input and output
  28        characters.
  29 

 200 
 201                    By default, disks are identified by instance names such as
 202                    ssd23 or md301. Combining the -n option with the -x option
 203                    causes disk names to display in the cXtYdZsN format which
 204                    is more easily associated with physical hardware
 205                    characteristics. The cXtYdZsN format is particularly useful
 206                    in FibreChannel (FC) environments where the FC World Wide
 207                    Name appears in the t field.
 208 
 209 
 210        -p
 211                    For each disk, report per-partition statistics in addition
 212                    to per-device statistics.
 213 
 214 
 215        -P
 216                    For each disk, report per-partition statistics only, no
 217                    per-device statistics.
 218 
 219 










 220        -r
 221                    Display data in a comma-separated format.
 222 
 223 
 224        -s
 225                    Suppress messages related to state changes.
 226 
 227 
 228        -t
 229                    Report the number of characters read and written to
 230                    terminals per second.
 231 
 232 
 233        -T u | d
 234                    Display a time stamp.
 235 
 236                    Specify u for a printed representation of the internal
 237                    representation of time. See time(2). Specify d for standard
 238                    date format. See date(1).
 239 

   1 IOSTAT(1M)                   Maintenance Commands                   IOSTAT(1M)
   2 
   3 
   4 
   5 NAME
   6        iostat - report I/O statistics
   7 
   8 SYNOPSIS
   9        /usr/bin/iostat  [-cCdDeEiImMnpPfFrstxXYz] [-l n] [-T u | d]
  10         [disk]... [interval [count]]
  11 
  12 
  13 DESCRIPTION
  14        The iostat utility iteratively reports terminal, disk, and tape I/O
  15        activity, as well as CPU utilization. The first line of output is for
  16        all time since boot; each subsequent line is for the prior interval
  17        only.
  18 
  19 
  20        To compute this information, the kernel maintains a number of counters.
  21        For each disk, the kernel counts reads, writes, bytes read, and bytes
  22        written. The kernel also takes hi-res time stamps at queue entry and
  23        exit points, which allows it to keep track of the residence time and
  24        cumulative residence-length product for each queue. Using these values,
  25        iostat produces highly accurate measures of throughput, utilization,
  26        queue lengths, transaction rates and service time. For terminals
  27        collectively, the kernel simply counts the number of input and output
  28        characters.
  29 

 200 
 201                    By default, disks are identified by instance names such as
 202                    ssd23 or md301. Combining the -n option with the -x option
 203                    causes disk names to display in the cXtYdZsN format which
 204                    is more easily associated with physical hardware
 205                    characteristics. The cXtYdZsN format is particularly useful
 206                    in FibreChannel (FC) environments where the FC World Wide
 207                    Name appears in the t field.
 208 
 209 
 210        -p
 211                    For each disk, report per-partition statistics in addition
 212                    to per-device statistics.
 213 
 214 
 215        -P
 216                    For each disk, report per-partition statistics only, no
 217                    per-device statistics.
 218 
 219 
 220        -f
 221                    Report ZFS-level statistics for ZFS pool and individual
 222                    vdevs in addition to per-device statistics.
 223 
 224 
 225        -F
 226                    Report ZFS pool and individual physical vdevs statistics
 227                    only, no per-device statistics.
 228 
 229 
 230        -r
 231                    Display data in a comma-separated format.
 232 
 233 
 234        -s
 235                    Suppress messages related to state changes.
 236 
 237 
 238        -t
 239                    Report the number of characters read and written to
 240                    terminals per second.
 241 
 242 
 243        -T u | d
 244                    Display a time stamp.
 245 
 246                    Specify u for a printed representation of the internal
 247                    representation of time. See time(2). Specify d for standard
 248                    date format. See date(1).
 249