Driver locked vmware tools

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Sign me up! What is ballooning? Method by which VMware host can reclaim memory from the Virtual machines. Is it really bad to give memory from Guest to Host? SQL Server is memory intensive application and requires adequate memory for smooth running. In addition to all this when memory is reclaimed from virtual machines available memory in windows drops triggering windows to page out the working set of all the processes and you will face all side affects discussed in A significant part of SQL Server process memory has been paged out.

In worst case it is better not to give memory for SQL Server instead of give and take back. Remember Max server Memory is also a factor which will impact the generation of execution plan by the optimizer, So plan generated when you have X GB of max server memory may not be the right plan to use when you have Y GB actual memory after ballooning reclaimed memory from guest OS.

What if hypervisor runs low in physical memory? It gives a hint that you have a poor consolidation. You can pick up the other Virtual machines that are not hosting production SQL Servers or SQL Servers from same Hypervisor and tweak reservations or Increase the maximum memory that can be reclaimed when the hypervisor is under memory pressure.

Ballooning can slowly take the memory from virtual machine in which SQL Server is hosted and can cause all the problems I mentioned above.

To make things confusing when you look at task manager you may not even realize that ballooning has reclaimed memory from Guest OS, Because total physical memory shown in performance tab includes the memory taken by ballooning driver.

VM memory performance counters can also be used. For example, 8 GB of memory is allocated to a virtual machine, the Task Manager shows that 1 GB is free though all running processes consume less than 3 GB. Where are the rest 4 GB? Memory overcommit is a hypervisor feature that allows you to allocate to virtual machines more memory than is available on a physical host, but without any guarantees that all requested memory can be allocated at a particular moment.

Memory overcommit allows to allocate virtual machines more densely due to dynamic memory distribution between VMs depending on the current host load the resources of idle VMs may be redistributed among more loaded ones. In Hyper-V, the same feature is implemented by Dynamic Memory.

Thus, the occupied amount of memory becomes unavailable to other applications in the guest OS, and the hypervisor can distribute free memory between other VMs. In Hyper-V Dynamic memory, a dmvsc. The memory overcommitment settings are managed by the hypervisor administrator.

How can you detect from within the guest VM that it actually has less physical memory available than what the guest operating system sees? To understand what is going on with the memory, you need to use RamMap tool by Mark Russinovich in one of the earlier cases, I have shown how to use this tool to diagnose an issue with the high memory usage by metafile on Windows Server.

After that on the Use Counts tab you can see that most of the memory 5. This is the memory that the hypervisor has occupied and distributed between other virtual machines using the balloon driver in the guest OS. It means that the hypervisor host does not have enough memory or the hypervisor administrator uses the memory limit policies for this VM. The current VM memory statistics in Hyper-V may be shown by separate performance counters in the Performance Monitor:.