FastX Memory Usage

FastX allows users to run multiple sessions which consume memory.  Unlike a traditional X Server (X-Win32), FastX requires a proxy X Server (the FastX Server) installed on the linux system to hold each session.  The extra overhead of the FastX Server limits the maximum number of Sessions that can run at any given time on the system.  Futhermore, the amount of memory allotted to a session will limit its maximum screen resolution.  System’s running in Single Application mode may have a resolution larger than the memory limits can handle.

Calculations

When determining the FastX Server requirements, perform the following calculation

RAM reqs = (width) x (height) x 4 x (2 + N)
where N is the number of users currently connected to the session

For example A session with a screen size of 1920×1080 will require at least 25mb of memory.  This calculation does not include the amount of memory required to run the applications (Desktops, terminals, etc) in the session itself

Configuring Memory Requirements

FastX allow System Administrators to configure the maximum amount of memory used per session.

  1. Set the Maximum Ram field to your Max Ram in kB in the Session Configuration page in the System section

This setting can also be set manually by editing the
/usr/lib/fastx2/config/session.json file