On 06/19/12 4:22 PM, Hugh E Cruickshank wrote: > The reason for the restriction to 32-bit is because of other software > that we must run that does not work correctly on a 64-bit OS. fix that other software. or run in 16GB. there's no excuse in 2012 for not supporting 64bit, even my budget laptop has 8GB of memory and a 64bit OS. as an example of the problems see this message, http://www.redhat.com/archives/rhelv5-list/2008-September/msg00194.html and its various followups... PAE was a kludge to let 32 bit OS's, normally limited to 4GB max memory address more. the kludge breaks things above 16GB in spite of the theoretical 64GB limit enforced by the hardware. also see this https://www.redhat.com/resourcelibrary/articles/articles-red-hat-enterprise-linux-6-technology-capabilities-and-limits EL *4* supported a nasty 'hugemem' kernel that could get you past 16GB but only at great overhead. this caused MANY problems and was discontinued in EL5 and 6 32bit systems, where 64bit is the correct choice for all modern servers. -- john r pierce N 37, W 122 santa cruz ca mid-left coast