System tools

Using tools such as iostat gives a good understanding of how the application interacts with the storage, for example, by using the following command:

iostat -dxctm 1

The previous code shows per block device usage, the areq-sz column (previously known as avgrq-sz) shows the average request size in kilobytes, making this a good starting point to understand the I/O size the application typically uses.

The output looks similar to the following screenshot:

In the preceding image, we could appreciate the block devices and their respective performance.