Memory Allocations for P2Ved servers

[RobBuxton]

Hi All,

I've been reading some of the threads on both VDI and Server deployments in a vmwware ESX environment.

One of the areas of interest was regarding memory settings. For XP clients it seemed that the guests were being deployed with quite low memory settings - 250-300MB

http://www.vmware.com/community/thread.jspa?threadID=83113&start=30&tstart=0

I cannot recall the thread but I believe there were also comments regarding servers, where the memory allocated to servers that were P2V'ed was reduced from the amount the original physical server had.

Our Host servers were memory constrained, we were running 4 servers that were 2 x dc HP DL 385's with 17GB each. We added an additional 8GB per server to provide more headroom.

So, is there a best practise, or at least a recommended approach for allocating memory for P2V'ed servers, or is it a matter of monitoring individual servers and tweaking them?

Does reducing the amount of memory allocated to a guest actually affect the amount of memory vmware gives it?

At this point we're not using resource pools, and have left the settings as unlimited with no resource settings.

TIA Rob.

[esiebert7625]

Converter will allocate the same amount of RAM the physical server for the virtual server. There was a bug in the 3.0.0 version of Converter that allocated slightly less memory (usually about 2-4K) then the physical server that was fixed in the 3.0.1 version of Converter. In a virtual environment you should carefully assess your VM's and only give them the memory they actually need. So if you had a physical server with 2GB of RAM but it is consistently using less then 1GB then you should reduce the VM's RAM to 1GB or less. ESX has alot of host memory saving techniques that help to reduce the amount of physical host memory a VM's uses by using page sharing, ballooning and memory taxes. Read through the below docs to get a better understanding of how memory works in ESX. Also whatever you allocate to the VM is the maximum amount of host memory that the VM can use, the "Unlimited" setting is misleading, a VM can never use more then what it is assigned.

The Role of Memory in ESX Server 3 - http://www.vmware.com/pdf/esx3_memory.pdf

Memory resource management in Vmware ESX Server - http://www.vmware.com/pdf/usenix_resource_mgmt.pdf

Understanding memory usage in Windows 2000 - http://www.microsoft.com/technet/prodtechnol/windows2000serv/tips/w2mem.mspx

Host Mem and Guest Mem % - http://www.vmware.com/community/thread.jspa?messageID=620581

RAM, Virtual Memory, Pagefile and all that stuff - http://members.shaw.ca/bsanders/WindowsGeneralWeb/RAMVirtualMemoryPageFileEtc.htm

Memory Limits - http://www.vmware.com/community/thread.jspa?messageID=632903&#632903 and http://www.vmware.com/community/thread.jspa?threadID=86075&messageID=653429#653429

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