IOSTAT(8) BSD System Manager's Manual IOSTAT(8)
iostat - report I/O statistics
iostat [-c count] [-M core] [-N system] [-w wait] [drives]
Iostat displays kernel I/O statistics on terminal, disk and cpu opera-
The options are as follows:
-c Repeat the display count times. The first display is for the time
since a reboot and each subsequent report is for the time period
since the last display. If no wait interval is specified, the de-
fault is 1 second.
-M Extract values associated with the name list from the specified
core instead of the default ``/dev/kmem''.
-N Extract the name list from the specified system instead of the de-
-w Pause wait seconds between each display. If no repeat count is
specified, the default is infinity.
Iostat displays its information in the following format:
tin characters read from terminals
tout characters written to terminals
Disk operations (this field is system dependent). The header of
the field is the disk name and unit number. If more than four disk
drives are configured in the system, iostat displays only the first
four drives. To force iostat to display specific drives, their
names may be supplied on the command line.
sps sectors transferred per second
tps transfers per second
msps milliseconds per average seek (including implied seeks and
us % of cpu time in user mode
ni % of cpu time in user mode running niced processes
sy % of cpu time in system mode
id % of cpu time in idle mode
/vmunix Default kernel namelist.
/dev/kmem Default memory file.
fstat(1), netstat(1), nfsstat(1), ps(1), systat(1), vmstat(1),
The sections starting with ``Interpreting system activity'' in Installing
and Operating 4.3BSD.
4th Berkeley Distribution June 6, 1993 1