1. if running windows 2003 {standard or enterprise] with over 1G of RAM, use the /3gb switch and userva-3030 switch. The /3gb swith changes the dividing line between user and kernal from the 2G point to the 3G point, effectively taking 1G away from Kernal and giving it to the user mode application (Exchange).
2. if running Windows 2000 Advanced server with over 1G of ram, use the /3gb switch and set the system pages key to 30,000. The userva switch in 2003 redistributes the pooled non paged bytes in order to compensate for the loss of page table entries when the /3gb switch is used. Setting system pages to 30,000 has the same effect.
3. Exchange is not capable of using more than 3G of RAM. Anything over 4G (3 for exchange and 1 for kernal) in the box is a waste. Yank the extra 2G and put it someplace where it will make a difference (your SQL server or other AWE aware application server).
Just for the true blue IBMers out there, IBM/Lotus gnoats in only capable of using 2G of RAM on the Windows platform. Why exactly did IBM arbitrarially cripple their application only on the Windows platform? (the AIX version has no such limit, and memory is the basis for performance tuning on the gnoats/dumbino platform). Does 3723 ring a bell?
5. DO NOT use the /PAE option. The /PAE option causes each page table entry to consume twice as much RAM. The net effect is to severely restrict PTEs (already in short supply because of the /3gb switch) and is a sure fire way to induce resource allocation errors (stop 3D, event ID 50 with a C000009A status code, etc.)
XMSRE
MOSMWNMTK, WKIL+, WMDM