[THIN] What happens when you overload a Citrix server?

  • From: "Landin, Mark" <Mark.Landin@xxxxxxxxxxxxxxxx>
  • To: "thin@xxxxxxxxxxxxx" <thin@xxxxxxxxxxxxx>
  • Date: Wed, 3 Nov 2010 11:13:11 -0500

Running CPS 4.5 on Windows 2003 Standard, 32-bit, SP2. 4 GB RAM.

Our primary application is Microsoft Dynamics GP as a published application. 
This has a memory footprint of 150-200MB per user, and we currently are seeing 
20-25 users per box (i.e., 5GB+ of memory footprint)

Recently our users have begun experiencing session disconnects, especially when 
coming back from being idle (walked away from their desk, turned to take a 
phone call, etc). We have no timeouts set on the ICA sessions and sometimes 
connection is lost even if they turn away for less than 5 minutes.

One theory is that the processes are dying because the servers are under memory 
stress (which they are), and that Windows is killing these processes to relieve 
the pressure. It may be killing the dynamics.exe process itself, or the ODBC 
connection between the application and the SQL server is being lost, which 
apparently causes the Dynamics GP application to wet itself and die.

So, my question(s) is/are:
-          When Windows is under severe memory pressure, will it just terminate 
processes? If so, how does it determine which ones?
-          When it does so, will there be anything logged in Event Viewer? If 
not, how can one confirm that in fact Windows is killing processed in order to 
reduce memory footprint?

If this is in fact the root cause, of course we have some options, like:
-          build more servers (scale out)
-          build bigger servers (scale up). We may be able to do 64-bit, but 
that will break new ground for us and I don't know how long that will take us 
to do. Would going to 2003 32-bit Enterprise Edition, and providing 8 or 16GB 
of RAM, help? Again, we are theorizing that the server is running out of RAM 
resources, not necessarily running out of kernel memory resources, so would 
throwing more RAM by way of Enterprise edition going to help?

Thanks for the assistance.

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