How to check disk activity in Linux
Disk read and write, or I/O activities affect the general system performance. It's often overlooked as some admins will only look into CPU activity when the system starts to slow down. The other aspect to look into when troubleshooting disk activity issue is disk latency.
Many Linux tools can be used to check disk activity, though generally, they're just another version of iostat and iotop. iostat monitors the I/O of block devices while iotop monitors the I/O of running processes. Another useful disk activity monitoring tool for Linux is ioping which monitors latency.
iostat, iotop and ioping can be installed and run from the terminal.
Steps to monitor disk IO activity in Linux:
- Launch terminal.
- Install sysstat package for your distribution.
$ sudo apt update && sudo apt install --assume-yes sysstat #Ubuntu and Debian derivatives $ sudo yum install --assumeyes sysstat # Red Hat and CentOS derivatives
- View I/O for all block devices using iostat.
$ iostat Linux 5.8.0-48-generic (host) Jumaat 09 Apr 2021 _x86_64_ (2 CPU) avg-cpu: %user %nice %system %iowait %steal %idle 0.25 0.01 0.18 0.01 0.00 99.54 Device tps kB_read/s kB_wrtn/s kB_dscd/s kB_read kB_wrtn kB_dscd loop0 0.00 0.02 0.00 0.00 1080 0 0 loop1 0.00 0.01 0.00 0.00 359 0 0 loop10 0.01 0.27 0.00 0.00 13555 0 0 loop11 0.00 0.00 0.00 0.00 14 0 0 loop2 0.00 0.02 0.00 0.00 1095 0 0 loop3 0.00 0.01 0.00 0.00 348 0 0 loop4 0.00 0.01 0.00 0.00 347 0 0 loop5 0.00 0.02 0.00 0.00 1073 0 0 loop6 0.00 0.01 0.00 0.00 350 0 0 loop7 0.01 0.28 0.00 0.00 13967 0 0 loop8 0.00 0.01 0.00 0.00 362 0 0 loop9 0.00 0.01 0.00 0.00 358 0 0 sda 2.95 16.00 95.17 0.00 800785 4762513 0 sdb 0.00 0.06 0.00 0.00 3233 12 0 sr0 0.00 0.00 0.00 0.00 2 0 0 - View I/O for a specific disk or block device on a set interval using iostat.
$ iostat /dev/sda -y 5 Linux 5.8.0-48-generic (host) Sabtu 10 Apr 2021 _x86_64_ (2 CPU) avg-cpu: %user %nice %system %iowait %steal %idle 3.67 0.00 2.73 0.00 0.00 93.60 Device tps kB_read/s kB_wrtn/s kB_dscd/s kB_read kB_wrtn kB_dscd sda 0.40 0.00 2.40 0.00 0 12 0 avg-cpu: %user %nice %system %iowait %steal %idle 4.73 0.00 2.52 0.00 0.00 92.75 Device tps kB_read/s kB_wrtn/s kB_dscd/s kB_read kB_wrtn kB_dscd sda 0.00 0.00 0.00 0.00 0 0 0 avg-cpu: %user %nice %system %iowait %steal %idle 3.70 0.00 3.28 0.00 0.00 93.02 Device tps kB_read/s kB_wrtn/s kB_dscd/s kB_read kB_wrtn kB_dscd sda 31.00 0.00 169.60 0.00 0 848 0 - Install iotop for your Linux distribution.
$ sudo apt update && sudo apt install --assume-yes iotop #Ubuntu and Debian derivatives $ sudo yum install --assumeyes iotop # Red Hat and CentOS derivatives
- Monitor disk activity for all running processes in almost realtime using iotop.
$ sudo iotop [sudo] password for user: Total DISK READ: 0.00 B/s | Total DISK WRITE: 0.00 B/s Current DISK READ: 0.00 B/s | Current DISK WRITE: 0.00 B/s TID PRIO USER DISK READ DISK WRITE SWAPIN IO> COMMAND 1 be/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % init splash 2 be/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [kthreadd] 3 be/0 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [rcu_gp] 4 be/0 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [rcu_par_gp] 6 be/0 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [kworker/0:0H] 9 be/0 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [mm_percpu_wq] 10 be/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [ksoftirqd/0] 11 be/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [rcu_sched] 12 rt/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [migration/0] 13 rt/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [idle_inject/0] 14 be/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [cpuhp/0] 15 be/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [cpuhp/1] 16 rt/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [idle_inject/1] 17 rt/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [migration/1] 18 be/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [ksoftirqd/1] 20 be/0 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [kworker/1:0H-kblockd] 21 be/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [kdevtmpfs] 22 be/0 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [netns] 23 be/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [rcu_tasks_kthre] 24 be/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [rcu_tasks_rude_] 25 be/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [rcu_tasks_trace] - Monitor only processes with I/O activity using iotop.
$ sudo iotop -o Total DISK READ: 0.00 B/s | Total DISK WRITE: 125.32 K/s Current DISK READ: 0.00 B/s | Current DISK WRITE: 148.82 K/s TID PRIO USER DISK READ DISK WRITE SWAPIN IO> COMMAND 7165 be/4 root 0.00 B/s 0.00 B/s 0.00 % 0.04 % [kworker/u256:1-events_freezable_power_] 316 be/3 root 0.00 B/s 125.32 K/s 0.00 % 0.03 % [jbd2/sda3-8] - Install ioping for your Linux distribution.
$ sudo apt update && sudo apt install --assume-yes ioping #Ubuntu and Debian derivatives $ sudo yum install --assumeyes ioping # Red Hat and CentOS derivatives
- Check disk latency using ioping.
$ sudo ioping /dev/sda 4 KiB <<< /dev/sda (block device 20 GiB): request=1 time=1.13 ms (warmup) 4 KiB <<< /dev/sda (block device 20 GiB): request=2 time=1.50 ms 4 KiB <<< /dev/sda (block device 20 GiB): request=3 time=2.49 ms 4 KiB <<< /dev/sda (block device 20 GiB): request=4 time=1.11 ms 4 KiB <<< /dev/sda (block device 20 GiB): request=5 time=807.4 us 4 KiB <<< /dev/sda (block device 20 GiB): request=6 time=2.02 ms
Author: Mohd Shakir Zakaria
Cloud architect by profession but always consider himself as a developer, entrepreneur and an opensource enthusiast.
Cloud architect by profession but always consider himself as a developer, entrepreneur and an opensource enthusiast.
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