A compact real-time viewer for per-process disk I/O to find who is blocking your system. 05.07.2026 | reading time: 2 min On a busy server, which process writes the disk relentlessly? iotop shows per-process disk I/O in real time so you can spot offenders and take action immediately. A real troubleshooting session When a web backend stalls, run iotop as root to capture active I/O: ```bash sudo iotop -o -b -n 3 -P ``` Sample output (truncated): ```text Total DISK READ: 0.00 B/s | Total DISK WRITE: 1.23 M/s 1234 be/4 nginx 0.00 B/s 1.15 M/s 0.00 % 10.1 % /usr/sbin/nginx 4321 be/4 backup 0.00 B/s 80.0 K/s 0.00 % 0.9 % /usr/bin/rsync ``` Here nginx is the obvious writer; stop or throttle that process and re-run iotop to confirm the effect. Options you will use Use `-o` to show only processes doing I/O, `-b` for batch mode suitable for scripts, `-n` to limit iterations, `-P` to show processes instead of threads and `-a` to display accumulated I/O since iotop started. Notes and limits iotop reads kernel per-task I/O accounting so it usually requires root or appropriate capabilities and kernel support for taskstats and task delay accounting (CONFIG_TASKSTATS and CONFIG_TASK_DELAY_ACCT); it attributes I/O to tasks but may not capture every kernel-internal I/O path. Other tools to pair with iotop For a complete diagnosis combine iotop with block-level and CPU-side views: `iostat` for device throughput, `pidstat` for per-process stats over time, and `blktrace` or BPF tools for deep block-layer tracing. Wrap-up and next step iotop is a focused, fast tool to find which process is causing disk load and it fits into a toolbox approach to performance troubleshooting; hone these skills and consider advancing with certifications such as CompTIA Linux+ or LPIC-1 and intensive exam prep at bitsandbytes.academy. Join Bits & Bytes Academy First class LINUX exam preparation. storage utilities processes troubleshooting This page was created with the help of AI.
