In this blog post, I will look at disk utilization and saturation.

In my previous blog post, I wrote about CPU utilization and saturation, the practical difference between them and how different CPU utilization and saturation impact response times. Now we will look at another critical component of database performance: the storage subsystem. In this post, I will refer to the storage subsystem as “disk” (as a casual catch-all). 

The most common tool for command line IO performance monitoring is

iostat

, which shows information like this:

root@ts140i:~# iostat -x nvme0n1 5
Linux 4.4.0-89-generic (ts140i)         08/05/2017      _x86_64_        (4 CPU)
avg-cpu:  %user   %nice %system %iowait  %steal   %idle
          0.51    0.00    2.00    9.45    0.00   88.04
Device:         rrqm/s   wrqm/s …

One of the new graphs added to Percona Monitoring and Management (PMM) is saturation metrics. This blog post explains how to use the information provided by these graphs.

You might have heard about Brendan Gregg’s USE Method  (Utilization-Saturation-Errors) as a way to analyze the performance of any system. Our goal in PMM is to support this method fully over time, and these graphs take us one step forward.

When it comes to utilization, there are many graphs available in PMM. There is the CPU Usage graph: …