Good afternoon,
I see a number of open threads regarding this topic, but not specifically related to vSphere 4.1.
As part of an implementation of an entirely fresh vSphere 4.1 deployment, a series of Windows Server 2008 R2 virtual machines have been deployed. However, it would appear that due to the feature of Windows Server 2008 'caching' available memory, vSphere isn't particuarly efficient with its resource usage at hypervisor level with regards to memory resources.
I see this as a major issue, as quite frankly the hypervisor not being unable to return what is simply unused memory from the guest virtual machines to the host for use by other guest VMs quite a bit of a constraint in the use of virtualisation.
Having read through a number of threads, discussions and blogs floating around the internet - I have come to no definitive resolution to this issue. I understand there was a known issue in 4.0 with TPS no neccessarily reporting the correct guest memory usage, but this appears to be marked as resolved in 4.1.
I have also tried setting the Mem.AllocGuestLargePage to 0 in the advanced settings of each host, but this has made no visible difference to the utilisation of the memory at host level.
In short, I am looking for others ideas and advice with regards to how potentially the memory of a vSphere host can be better managed when having multiple Windows Server 2008 R2 virtual machines.
Any input would be greatly apprecaited.