What type of problems do I may have running a 32 bit OS with a huge amount of RAM?

Alberto López Torres · 06-03-2009, 10:29 AM

I have read a lot of information regarding the problems that we can have running a 32 bit Linux with a Huge Amount of Ram 16GB+.

For example I have a 32 bit Red Hat server (2 Intel Quad CPU's) with 32GB ram. We are using the Hugemem Kernel to recognize the 32 GB of Ram. I know that I should move to 64bits, but what I would like to know the problems that I could have using such amount of RAM in a 32 bit environment.

Thanks

MS3FGX · 06-03-2009, 10:46 AM

It may or may not be a problem for your specific situation, but more than 4 GB of RAM on 32 bit hardware is not an ideal situation.

Normally 32 bit hardware and software is limited to 4 GB of RAM, as that is the maximum size of the address space. To work around this (until 64 bit hardware becomes dominant), a technique called Physical Address Extension is used.

To put it very simply, PAE breaks your total RAM up into virtual memory areas that are no larger than 4 GB each. Individual processes have access to these virtual memory banks through pages. In other words, no 32 bit application ever sees more than 4 GB of RAM at the same time.

This means that on a machine with 16 GB of RAM, you could have 4 processes each taking up 4 GB. But one process couldn't use the whole 16, or even be aware it was there.