What happens to memory pages that cannot be efficiently compressed in vSphere 6?

In vSphere 6, when memory pages cannot be efficiently compressed, the system will write those pages to disk. This mechanism is part of the memory management capabilities in virtualization, where the hypervisor makes decisions on optimizing and managing memory resources effectively.

Writing pages to disk allows the hypervisor to manage memory more flexibly and ensures that the active memory usage stays efficient while providing a solution for memory pressure situations. This process can involve using a swap file or leveraging VMkernel memory, enabling the system to maintain performance levels even when physical memory resources are constrained.

The other options don't accurately reflect the behavior of vSphere's memory management. For example, simply deleting pages would lead to loss of data, whereas sending them for archival or reallocation does not align with how vSphere handles memory that it cannot efficiently compress. The approach of writing to disk allows for a more strategic use of limited resources.