iostat [-CUdKIoT?] [-c count] [-n devs] [-w wait] [drives]
displays kernel I/O statistics on terminal, device and cpu operations.
The first statistics that are printed are averaged over the system uptime.
Display statistics for the first disk device every second ad infinitum.
/usr/sbin/iostat -w 1 disk0
KB/t tps MB/s 5.04 75 0.37 0.00 0 0.00 8.00 4 0.03 13.56 16 0.21 4.39 433 1.85 4.01 4074 15.95 4.00 4156 16.25 4.01 3907 15.29 4.09 1681 6.71
/usr/sbin/iostat -c 8
total statistics every three seconds ad infinitum.
/usr/sbin/iostat -Iw 3
total statistics using the
old-style 9 times, with a 2 second wait
between each measurement/display. The -d flag generally disables the TTY and CPU displays, but since
the -T and -C flags are given, the TTY and CPU displays will be displayed.
/usr/sbin/iostat -odICTw 2 -c 9
The sections starting with Interpreting system activity in Installing and Operating 4.3BSD.
/usr/bin/iostat [ options... ] [
system activity reporter
cumulative statistic counters maintained by the operating system.
Sampling input comes from a previously recorded, binary activity file, specified using
The starting and ending time of the report can be restricted using the -e and -s options. Here, the time field is specified in the form hh[:mm[:ss]]. Finally, the -i option can be used to select the sampling interval. Only records at least seconds apart will be reported. When the -i option is not used, all of the previously recorded interval samples are reported. Due to the nature of on-going sample collection, the data is reported in a verbose mode when more than one sampling option is specified. Column headers are printed at the beginning of the report; averages are printed when the sar command terminates.
OPTIONS The following options restrict the sample set that sar reports. -d Report disk activity. device The BSD name of the device. r+w/s The number of reads and writes per second. blks/s Number of blocks (in device's default blocksize) transferred to a device per second. -g Report page-out activity. pgout/s The number of pages paged out per second. -p Report page-in and page fault activity pgin/s The number of pages paged in per second. pflts/s The number of faults that caused a page to be copied in per second. vflts/s The number of times vm_fault routine has been called. -n mode Report network activity with modes DEV, EDEV, or PPP. Multiple network modes can be specified. DEV The DEV mode reports network device statistics. The following information is displayed for each interface. IFACE The network interface name. Ipkts/s The number of packets received per second. Ibytes/s The number of bytes received per second. Opkts/s The number of packets sent per second. Obytes/s The number of bytes sent per second. EDEV The EDEV mode reports network device error statistics. The following information is displayed for each interface. IFACE The interface name. Ierrs/s The input errors per second. Oerrs/s The output errors per second. Coll/s The collisions that occurred per second. Drops/s The number of dropped packets per second. PPP The PPP mode must be specified in order to display ppp connections in the network statistics. This will also turn on the PPP modify mode in sadc (8) when sampling data is not being read from a file. By default, both the collection and reporting of ppp statistics is turned off. See sadc (8). -u Report CPU activity (default) %usr, %sys, and %idle These report the percentage of time running in user mode, system mode and idle. FILES /var/log/sa/sadd Default daily activity file that holds the binary sampling data. dd are digits that represent the day of the month. SEE ALSO fs_usage(1), netstat(1), sc_usage(1), top(1), vm_stat(1), iostat(8), sa1(8), sa2(8), sadc(8) > sudo sar -d 5 30 20:40:57 device r+w/s blks/s New Disk: [disk0] IODeviceTree:/PCI0@0/SATA@B/PRT0@0/PMP@0/@0:0 20:41:02 disk0 1 9 20:41:07 disk0 8 458 20:41:12 disk0 8 361 20:41:17 disk0 13 332 20:41:22 disk0 0 6 20:41:27 disk0 0 6 20:41:32 disk0 1 9 ^C Average: 4 80