Every few days we have to reboot a few servers due to high memory utilization. These servers are running in an VMWare ESXi v4.1 environment. The ESXi server is not over-committed. It still has 17G free. In the VMWare ESXi configuration for the problem servers, I've set Memory Reservations based on another posting I read, but didn't seem to help.
We have 3 Windows 2008 R2 SP1 guest VMs running on the host that exhibit the problem. These VMs are used as test environments and are similarly configured, running IIS and Sql Server. The memory allocated to each VM is 8 GB, and the Sql Server memory usage is capped at 1.5 GB.
We frequently notice that the memory consumption in all these VMs have gone up to 8 GB, making the guests slow and almost unusable due to the memory pressure. The Performance Tab in the Task Manager shows this high memory usage. However, when we look at the individual processes in the Task Manager, we do not see any process that can account for the amount of memory being used. The total memory usage shown there can perhaps account for 2 - 2.5 GB, but there is no indication of where all the remaining memory is being used for. Restarting Sql Server or IIS doesn't help. rebooting the guest is the only step that releases the memory.
We have tried the memory reservation suggestion mentioned in this post, but that didn't help : What's using all my memory?
Any advice would be appreciated.