---
name: "iotop"
section: "1m"
platform: "macos"
package: "dtrace"
version: "413"
release: "macOS 26.5"
platforms: ["macos"]
url: "https://new.carta.tech/iotop/1m"
---

# iotop(1m)

display top disk I/O events by process. Uses DTrace.

## NAME

iotop - display top disk I/O events by process. Uses DTrace.

## SYNOPSIS

**iotop** \[-C\] \[-D\|-o\|-P\] \[-j\|-Z\] \[-d device\] \[-f filename\] \[-m mount\_point\] \[-t top\] \[interval \[count\]\]

## DESCRIPTION

iotop tracks disk I/O by process, and prints a summary report that is refreshed every interval.

This is measuring disk events that have made it past system caches.

Since this uses DTrace, only users with root privileges can run this command.

## OPTIONS

- \-C

  don't clear the screen

- \-D

  print delta times - elapsed, us

- \-j

  print project ID

- \-o

  print disk delta times, us

- \-P

  print %I/O (disk delta times)

- \-Z

  print zone ID

- \-d device

  instance name to snoop (eg, dad0)

- \-f filename

  full pathname of file to snoop

- \-m mount\_point

  mountpoint for filesystem to snoop

- \-t top

  print top number only

## EXAMPLES

- Default output, print summary every 5 seconds

  \#  **iotop**

- One second samples,

  \#  **iotop** 1

- print %I/O (time based),

  \# **iotop** -P

- Snoop events on the root filesystem only,

  \# **iotop** -m /

- Print top 20 lines only,

  \# **iotop** -t 20

- Print 12 x 5 second samples, scrolling,

  \# **iotop** -C 5 12

## FIELDS

- UID

  user ID

- PID

  process ID

- PPID

  parent process ID

- PROJ

  project ID

- ZONE

  zone ID

- CMD

  command name for the process

- DEVICE

  device name

- MAJ

  device major number

- MIN

  device minor number

- D

  direction, Read or Write

- BYTES

  total size of operations, bytes

- ELAPSED

  total elapsed times from request to completion, us (this is the elapsed  time from the disk request (strategy) to the disk completion (iodone))

- DISKTIME

  total times for disk to complete request, us (this is the time for the  disk to complete that event since it's last event (time between iodones), or, the time to the strategy if the disk had been idle)

- %I/O

  percent disk I/O, based on time (DISKTIME)

- load

  1 minute load average

- disk\_r

  total disk read Kb for sample

- disk\_w

  total disk write Kb for sample

## DOCUMENTATION

See the DTraceToolkit for further documentation under the  Docs directory. The DTraceToolkit docs may include full worked examples with verbose descriptions explaining the output.

## EXIT

iotop will run forever until Ctrl-C is hit, or the specified interval is reached.

## AUTHOR

Brendan Gregg \[Sydney, Australia\]

## SEE ALSO

iosnoop(1M), dtrace(1M)