How To Use Iotop To Locate High I/O on CentOS 6
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If you are a Linux system administrator, one of your common maintenance tasks is to quickly determining which processes consume large amounts of disk I/O before you can find a solution accordingly.
You can use
iotop to get this task done. Unlike
iostat, which can only display the summary of disk I/O,
iotop can display the I/O usage of each process or thread. This will allow you to easily determine the most I/O consuming processes which are slowing down the system.
In this article, we will be covering the process of installing
iotop on a CentOS 6 x64 server instance.
Before further reading, you need to:
- An ITWeb.Services instance running CentOS 6 x64.
- A sudo user.
On CentOS 6, You can install iotop with the following command:
sudo yum install iotop
For security purposes, non-root users who don’t own sudo privileges have been forbidden to launch the iotop utility. You must be the root or a sudo user before you can launch the iotop:
iotop interface is rather intuitive. On the top of the screen, you can see the total disk read speed and the total disk write speed. then you can see a highlighted row of parameters explained as below:
- PID: the process ID
- PRIO: the I/O priority
- USER: the user who is using the command
- DISK READ: the disk output bandwidth
- DISK WRITE: the disk input bandwidth
- SWAPIN: the percentage of time the thread spent while swapping in
- IO: the percentage of time the thread spent while waiting on I/O
- COMMAND: the command name
Under the highlighted line, you can see all of the running processes in the system, sorted by one of the parameters mentioned above, one process a line.
You can use the following keys to control the display:
- The left and right arrows: change the sorting column which by default is IO.
- r: toggle the sorting order.
- o: toggle between “only showing processes or threads actually doing I/O” and “showing them all”.
- p: toggle between “only showing processes, not all threads” and “showing processes and all threads”.
- a: toggle between “showing accumulated I/O” and “showing I/O bandwidth”.
- q: quit.
- any another key: refresh.
This concludes our tutorial on how to install and use
iotop. Thank you for reading.
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