Switch to SpeakEasy.net DSL

The Modular Manual Browser

Home Page
Manual: (v7man)
Apropos / Subsearch:
optional field

IOSTAT(1M)                                                          IOSTAT(1M)

       iostat - report I/O statistics

       iostat [ option ] ...  [ interval [ count ] ]

       Iostat delves into the system and reports certain statistics kept about
       input-output activity.  Information is kept about up to three different
       disks  (RF,  RK,  RP) and about typewriters.  For each disk, IO comple-
       tions and number of words transferred are counted; for typewriters col-
       lectively,  the  number  of  input  and  output characters are counted.
       Also, each sixtieth of a second, the state of each disk is examined and
       a tally is made if the disk is active.  The tally goes into one of four
       categories, depending on whether the system is executing in user  mode,
       in  `nice'  (background)  user mode, in system mode, or idle.  From all
       these numbers and from the known transfer rates of the  devices  it  is
       possible  to determine information such as the degree of IO overlap and
       average seek times for each device.

       The optional interval argument causes iostat to report once each inter-
       val seconds.  The first report is for  all time since a reboot and each
       subsequent report is for the last interval only.

       The optional count argument restricts the number of reports.

       With no option argument iostat reports for  each  disk  the  number  of
       transfers  per  minute, the milliseconds per average seek, and the mil-
       liseconds per data transfer exclusive of seek time.  It also gives  the
       percentage  of time the system has spend in each of the four categories
       mentioned above.

       The following options are available:

       -t     Report the number of characters of terminal  IO  per  second  as

       -i     Report  the  percentage  of time spend in each of the four cate-
              gories mentioned above, the percentage of  time  each  disk  was
              active  (seeking  or  transferring),  the percentage of time any
              disk was active, and the percentage of time spent in `IO  wait:'
              idle, but with a disk active.

       -s     Report  the  raw  timing  information: 32 numbers indicating the
              percentage of time spent in each of the possible  configurations
              of 4 system states and 8 IO states (3 disks each active or not).

       -b     Report on the usage of IO buffers.

       /dev/mem, /unix