How to Monitor Disk IO in htop on Ubuntu

This article provides a step-by-step method for monitoring disk input and output activity using the htop process viewer on Ubuntu. It covers installation, configuration of specific I/O columns, and how to interpret the data to spot performance bottlenecks.

Install htop

If htop is not already installed on your Ubuntu system, open your terminal and run the following command:

sudo apt update
sudo apt install htop

Launch htop

Start the application by typing the following command in your terminal:

htop

Configure Display Columns

By default, htop may not show disk I/O metrics. To enable them, press the F2 key to open the Setup menu. Navigate to the “Columns” section. Use the spacebar to select and add the following columns to the displayed list:

• IO_READ_RATE
• IO_WRITE_RATE

Press F10 or Esc to save changes and return to the main view. You should now see two new columns indicating the read and write speed for each process.

Interpret the Data

The values in these columns represent the current rate of data transfer. IO_READ_RATE shows how much data a process is reading from the disk per second, while IO_WRITE_RATE shows how much data it is writing. High values indicate heavy disk usage by that specific process.

Sort by Disk Usage

To quickly identify which process is consuming the most disk resources, click on the column header with your mouse or press F6 to open the sort menu. Select IO_READ_RATE or IO_WRITE_RATE to sort the process list by disk activity in descending order. This allows you to immediately pinpoint the applications causing high I/O load.