64bit memory and VM question
Posted on 2010-09-14
Our environment is ESX 3.5, Windows 2003 SP2 Enterprise servers guests.
We have an application running on a VM guest. It is a 32bit app, but we have assigned 4GB RAM just in case. We figure that if the RAM is not used, we are not actually losing anything, since we are not directly paying for its exclusive use like we would do with a physical box.
We're now in the midst of a refresh, and we're upgrading to Windows 2008 R2 servers which are all 64bit OS.
I'm trying to work out what amount of RAM to assign the guests that will host the application.
- Should we continue to assign 4GB
- Is there any benefit of assigning more than 4GB for a 32bit app (I read on EE that 32bit apps could only see 4GB virtual address space per process, but I guess there could be multiple processes)
- The third option I'm thinking is using Perfmon to baseline our existing servers and find an average of memory use over, say, 48 hours. Does anyone know what the best counter to use would be and is it simply a case of running Perfmon for 48 hours and using the average value for whatever counter? Question is, does 2008 handle memory in any differernt way than 2003 server?