Plesk offers a convenient way to update your system packages installed on your Linux server. This tool is the equivalent of running a "yum update" or "apt-get update" command on your Linux server.
System updates are important to conduct as these system packages may contain security exploits and or bugs that are addressed through these updates. It is recommended to keep your system packages up to date at all times.
You can access the System updates screen by going to Tools & Settings, and then under Server Management click the System Updates button. The System Updates page looks like this:
From here you can select which packages you would like to update, or you could simply press the Update All button at the top of the page to update all of your system packages at once. Pressing the Update All button will bring up this pop up confirming which packages will be updated, you can press the OK button to start the update. These updates should not take your websites or server offline although they may force some services to restart, killing any ongoing processes.
Once you press the OK button, the pop up will disappear. You will notice that the update is actually taking place in the background, you can see the progress in the bottom right hand corner of your page.
Once your updates are done, you will see a success or failure message shown in this same location (bottom right hand corner).
You can now refresh your page to see that there are no available updates.