Sysstat is a robust logging and performance monitoring utility for Linux/Unix systems. It can be used to keep track of system performance and usage activity.

Sysstat saves the statistics collected in a file that can be exported into various formats such as JSON, CSV, etc. Though many Linux distributions include GUI-based monitoring apps, sysstat is especially useful in a server setting.

Here at Ibmi Media, as part of our Server Management Services, we regularly help our Customers to perform related Linux system Monitoring queries.

In this context, we shall look into how to use the sysstat tool to collect key system information on Linux.

For further information on Systat, check out the Sysstat Documentation http://sebastien.godard.pagesperso-orange.fr/documentation.html.

How to install Sysstat ?

The Sysstat package is available in the default package repositories and may be installed with the commands below:

$ sudo apt install sysstat

Common usage of Sysstat

The sysstat suite comprises various tools that help collect information on CPU and I/O statistics. Here, we will discuss how to use the tools to get system information. These tools include:

• iostat – shows an overview of CPU and I/O statistics for drives and partitions
• mpstat– displays processor statistics.
• pidstat – gives an overview of I/O, memory statistics for processes.
• sar – used for collecting and saving all the system activities and reports.
• sadc- collects system usage activity and writes it to a file.

1.  How to Check CPU usage ?

Sars is used to collect system statistics such as CPU utilization, memory among others. View your CPU utilization statistics for the day. Sar monitors data every 10 minutes by default:

$ sar -u

To display real-time CPU utilization for a set period of time, specify the intervals in seconds followed by the number of entries to report. For instance, to view total CPU utilization every 3 seconds for a total of 15 times run:

$ sar -u 3 15

2. How to Check individual CPU usage ?

Currently, the majority of PCs have several cores. To display the statistics of each core use the sars command followed by the "-P ALL" parameter as shown below:

$ sar -P ALL 1 1

This will display the system's four cores with the same time interval and output parameters applied.

3. How to Check memory usage ?

To display the amount of memory in use at a particular time use the -r option:

$ sar -r

4. How to Display device report ?

Use the iostat command to display a device report showing current data transfer per second (tps), average block rate, and data read and write statistics. Run the following command:

$ iostat -d

The columns in the output represent:

• tps – transfers per second issued on the device
• kB_read/s – shows the amount of kilobytes read in blocks per second
• kB_wrtn/s – the amount of data written to devices in kbs per second
• kB_read – total kilobytes read
• kB_wrtn – total number of kilobytes written

To view extended I/O statistics run:

$ iostat -x

How to View current processes ?

The pidstat command is used to keep track of each individual task managed by the kernel. To get information about the running processes, run the pidstat command followed by -d parameter:

$ pidstat -d

You can also pidstat with the -r option to analyze memory usage with particular processes:

$ pidstat -r

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