32v 1m iostat

IOSTAT(1M) UNIX Programmer's Manual IOSTAT(1M)

NAME

    iostat - report I/O statistics

SYNOPSIS

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

DESCRIPTION

    _I_o_s_t_a_t 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 termi-
    nals.  For each disk, IO completions and number of words
    transferred are counted; for terminals collectively, the
    number of input and output characters are counted.  Also,
    each sixtieth of a second, the state of each disk is exam-
    ined 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 pos-
    sible to determine information such as the degree of IO
    overlap and average seek times for each device.

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

    The optional _c_o_u_n_t argument restricts the number of reports.

    With no option argument _i_o_s_t_a_t reports for each disk the
    number of transfers per minute, the milliseconds per average
    seek, and the milliseconds 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 well.

    -i   Report the percentage of time spend in each of the four
         categories mentioned above, the percentage of time each
         disk was active (seeking or transferring), the percen-
         tage 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 indicat-
         ing the percentage of time spent in each of the possi-
         ble configurations of 4 system states and 8 IO states
         (3 disks each active or not).

    -b   Report on the usage of IO buffers.

FILES

    /dev/kmem, /unix