iotop

Interactive real-time display of disk I/O per process.

low risk

interactive breakdown — edit the command and press Explain
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⚠ Risks & cautions
What it does

iotop shows disk read/write rates per process in real time, similar to top for disk I/O. Invaluable for identifying which process is generating excessive disk activity that affects performance.

Common flags
FlagMeaning
-o --onlyShow only processes doing I/O
-b --batchNon-interactive batch mode
-n --iterNumber of iterations
-d --delayDelay between iterations in seconds
Examples
iotop -oShow only processes actively doing I/O · explain & risk-check →
iotop -b -n 3 -oThree batch snapshots of active I/O · explain & risk-check →
iotop -b -n 1 -o | head -20Quick top-I/O-processes snapshot for scripting · explain & risk-check →
Pro tip

Run `iotop -o` when a system is slow and top shows high I/O wait — iotop immediately reveals which process is the I/O culprit without guessing.

Related
iostat vmstat dmesg
Open the full explainer →More in Debugging & Performance

Reference text is hand-written and may be incomplete — check man iotop for your version. Test destructive commands on a non-production system first.