NetWare 6 RAM Issues

Articles and Tips: qna

01 Sep 2002

I'm having a hard time trying to find out if Portal (Tomcat) can make use of the RAM above 4 GB in a NetWare 6 box. A local university is trying to ramp up their Novell Portal Services (NPS) environment and is waiting for an answer on this one.

Ramping RAM with Raphael

Dear: Ramping : The NetWare Java Virtual Machine (JVM) v1.3 on NetWare 6 is only capable of using up to 485 MB. There are some other options, however:

Set Tomcat's -Xmx switch to 485 (making it bigger doesn't do anything and could cause problems).
There is an unsupported switch in NetWare 6 that will allow processes to use more than 485 MB. You could try this, but if it breaks other stuff it won't be a shock. The switch is "server -u1000000000" for 1 GB. You could then increase your Tomcat -Xmx switch to that size. I have no idea if this will scale beyond 4 GB.
You can run multiple threads of Tomcat, and round robin them behind Apache--all on one box. The configuration is not straightforward, however, and I haven't seen it documented well anywhere. All the information you need is at http://www.apache.org. The downside to this approach is there is a lot of CPU cycles used and I am not sure if this will scale beyond 4 GB.
Run Tomcat on something other than NetWare. The 485 MB limit is an unfortunate limit of the NetWare JVM v1.3. The NetWare JVM v1.4 looks to improve the situation drastically.

Each JVM implementation (on each platform) have vastly varying amounts of RAM that they can allocate to a Tomcat process:

NetWare/NW JVM1.3--maximum 485 MB (true for any process) (This can be increased with the -u server.exe switch, but it isn't supported yet).
Win32/Sun JVM1.3--maximum 1.3 GB
Linux/Sun JVM1.3--maximum 1.8 GB
Solaris/Sun JVM1.3--maximum 3.84 GB

As yet I haven't been able to find the limits for the new Sun 1.4 JVMs. When I do, we could post them in this column.

* Originally published in Novell AppNotes

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