NAME

iostat − report I/O statistics

SYNOPSIS

iostat [ interval [ count ] ]

DESCRIPTION

Iostat iteratively reports the number of characters read and written to terminals, and, for each disk, the number of seeks, transfers per second, disk sectors transfered per second, and the milliseconds per average seek.  It also gives the percentage of time the system has spent in user mode, in user mode running low priority (niced) processes, in system mode, and idling. 

To compute this information, for each disk, seeks and data transfer completions and number of disk sectors are counted; for terminals collectively, the number of input and output characters are counted.  From these numbers and given the transfer rates of the devices it is possible to determine average seek times for each device (which includes all forms of disk latency). 

The optional interval argument causes iostat to report once each interval seconds.  The first report is an average 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. 

EXAMPLE

ttyxp0sd0sd1cpu
 tin tout bps tps msps  bps tps msps  bps tps msps  us ni sy id
  38  543  36   3  0.0    0   0  0.0    3   0  0.0   9  2 17 72

For terminals, tin is the number of characters received per second from terminals and tout is the number of characters transmitted per second to terminals.  For disks, bps is the number of blocks (512 byte disk blocks) transferred per second, tps is the number of transfers per second, and msps is the number of milliseconds per seek.  The latter is always 0.0 since the number of seeks is not kept by DYNIX.  For cpus, us is the percentage of time spent in user mode, ni is the percentage of time spent in user mode at lower priority (niced), sy is the percentage of time spent in system (kernel) mode, and id is the percentage of time spent idle. 

FILES

/dev/kmem
/dynix

SEE ALSO

vmstat(1)

4BSD