iotop

Top-like utility for monitoring disk I/O usage by processes in real-time

TLDR

Start iotop (shows all processes)

$ sudo iotop

Show only processes doing I/O

$ sudo iotop -o

Show accumulated I/O instead of bandwidth

$ sudo iotop -a

Don't show threads (processes only)

$ sudo iotop -P

Non-interactive mode with specific iterations

$ sudo iotop -b -n [10]

Monitor specific process by PID

$ sudo iotop -p [PID]

Monitor specific user

$ sudo iotop -u [username]

Update every N seconds

$ sudo iotop -d [2]

SYNOPSIS

iotop [-oaPbkqtd] [-n iterations] [-p pid] [-u user]

iotop is a top-like utility for monitoring disk I/O usage by processes in real-time. It displays a live view of read/write operations per process, helping identify which applications are causing disk activity.The display shows columns for thread/process ID, priority, user, disk read rate, disk write rate, swap-in percentage, I/O percentage, and command. The I/O percentage indicates time spent waiting for I/O operations.Accumulated mode (-a) is useful for finding processes that perform sporadic but significant I/O. Instead of showing instantaneous bandwidth, it shows total bytes read/written since iotop started, revealing processes that did heavy I/O even briefly.The tool requires root privileges to access I/O accounting data from the kernel's taskstats interface. The kernel must have CONFIGTASKIO_ACCOUNTING enabled (most distributions include this).Batch mode enables logging I/O activity over time. Combined with -t for timestamps, it can diagnose intermittent I/O issues by capturing activity during problem periods.

PARAMETERS

-o, --only

Show only processes actually doing I/O.

-a, --accumulated

Show accumulated I/O instead of bandwidth.

-P, --processes

Show processes only, not threads.

-b, --batch

Non-interactive batch mode (for logging).

-n NUM

Number of iterations before exiting.

-d SEC

Delay between updates in seconds.

-p PID

Monitor specific process(es).

-u USER

Monitor processes for specific user(s).

-k, --kilobytes

Use kilobytes instead of human-readable.

-t, --time

Add timestamp to each line (batch mode).

-q, --quiet

Suppress header lines (batch mode). Use twice to suppress column names too.

--no-help

Suppress interactive help line.

INTERACTIVE KEYS

Left/Right arrows

Change sort column.

Reverse sort order.

Toggle showing only active processes.

Toggle showing processes/threads.

Toggle accumulated/bandwidth mode.

Quit.

Change ionice priority of selected process.

INSTALL

sudo pacman -S iotop

sudo apk add iotop

sudo zypper install iotop

nix profile install nixpkgs#iotop

CAVEATS

Requires root privileges. Kernel must have IO accounting enabled (CONFIGTASKIO_ACCOUNTING). Shows disk I/O, not network or other I/O. May add slight overhead. Some I/O may be attributed to kernel threads rather than user processes.

HISTORY

iotop was written by Guillaume Chazarain and first released around 2007. It was created to fill the gap in Linux monitoring tools -- while CPU and memory monitoring had top, disk I/O monitoring lacked an equivalent. The tool relies on kernel features (taskstats) added in Linux 2.6.20. An alternative Rust-based reimplementation called iotop-c exists with a similar interface.