iostat - Interactively report I/O and CPU statistics. iostat(1) iostat(1) NAME iostat - report I/O statistics SYNOPSIS iostat [-t] [interval [count]] DESCRIPTION iostat iteratively reports I/O statistics for each active disk on the system. Disk data is arranged in a four-column format: Column Heading Interpretation device Device name bps Kilobytes transferred per second sps Number of seeks per second msps Milliseconds per average seek If two or more disks are present, data is presented on successive lines for each disk. To compute this information, seeks, data transfer completions, and the number of words transferred are counted for each disk. Also, the state of each disk is examined HZ times per second (as defined in <sys/param.h>) and a tally is made if the disk is active. These numbers can be combined with the transfer rates of each device to determine average seek times for each device. With the advent of new disk technologies, such as data striping, where a single data transfer is spread across several disks, the number of milliseconds per average seek becomes impossible to compute accurately. At best it is only an approximation, varying greatly, based on several dynamic system conditions. For this reason and to maintain backward compatibility, the milliseconds per average seek ( msps ) field is set to the value 1.0. Options iostat recognizes the following options and command-line arguments: -t Report terminal statistics as well as disk statistics. Terminal statistics include: tin Number of characters read from terminals. tout Number of characters written to terminals. us Percentage of time system has spent in user mode. ni Percentage of time system has spent in user mode running low-priority (nice) processes. sy Percentage of time system has spent in system mode. id Percentage of time system has spent idling. interval Display successive lines which are summaries of the last interval seconds. The first line reported is for the time since a reboot and each subsequent line is for the last interval only. count Repeat the statistics count times. EXAMPLES Show current I/O statistics for all disks: iostat Display I/O statistics for all disks every 10 seconds until INTERRUPT or QUIT is pressed: iostat 10 Display I/O statistics for all disks every 10 seconds and terminate after 5 successive readings: iostat 10 5 Display I/O statistics for all disks every 10 seconds, also show terminal and processor statistics, and terminate after 5 successive readings: iostat -t 10 5 WARNINGS Users of iostat must not rely on the exact field widths and spacing of its output, as these will vary depending on the system, the release of HP-UX, and the data to be displayed. AUTHOR iostat was developed by the University of California, Berkeley, and HP. FILES /usr/include/sys/param.h SEE ALSO vmstat(1). |