What is the effect of applying a memory limit these virtual machines?

A new ESXi host is set up with two virtual machines. A memory limit is applied so that users will have predictable performance as virtual machines are added to the host.

What is the effect of applying a memory limit these virtual machines?

A.
No physical memory will be granted above the limit, unless expandable reservations arte enabled.

B.
No physical memory will be granted above the limit, but disk pages can be used.

C.
Physical memory will be granted above the limit under normal conditions, but he limit will be enforced if connection occurs.

D.
Physical memory will be granted above the limit under normal conditions. Disk pages will be used if connection occurs.

Explanation:
Expandable Reservation:
Use this check box to indicate that more than the specified reservation should be allocated if resources are available in a parent.

Shares:
Specify the relative priority for a virtual machine if more than the reservation is available.

Reservation:
Is a guaranteed lower bound on the amount of physical memory that the host reserves for the virtual machine, even when memory is overcommitted. Set the reservation to a level that ensures the virtual machine has sufficient memory to run efficiently, without excessive paging.

After a virtual machine has accessed its full reservation, it is allowed to retain that amount of memory and this memory is not reclaimed, even if the virtual
machine becomes idle. For example, some guest operating systems (for example, Linux) might not access all of the configured memory immediately
after booting. Until the virtual machines accesses its full reservation, VMkernel can allocate any unused portion of its reservation to other virtual machines.
However, after the guests workload increases and it consumes its full reservation, it is allowed to keep this memory.

Limit: Is an upper bound on the amount of physical memory that the host can allocate to the virtual machine. The virtual machines memory allocation is also
implicitly limited by its configured size. Overhead memory includes space reserved for the virtual machine frame buffer and various virtualization data structures.

6 Comments on “What is the effect of applying a memory limit these virtual machines?

    1. daniel says:

      VSphere Resource Managemnt page 45:
      Expandable Reservation When the check box is selected (default), expandable reservations are considered during admission control.
      If you power on a virtual machine in this resource pool, and the combined reservations of the virtual machines are larger than the reservation of the resource pool, the resource pool can use resources from its parent or ancestors.

      VSphere Resource Managemnt page 12:

      Resource Allocation Limit
      Limit specifies an upper bound for CPU, memory, or storage I/O resources that can be allocated to a virtual machine. A server can allocate more than the reservation to a virtual machine, but never allocates more than the limit, even if there are unused resources on the system. The limit is expressed in concrete units (megahertz,
      megabytes, or I/O operations per second). CPU, memory, and storage I/O resource limits default to unlimited. When the memory limit is unlimited, the amount of memory configured for the virtual machine when it was created becomes its effective limit in most
      cases.

  1. w1ll1ng says:

    I agree with Brett. The formula that defines the amount of virtual machine memory that will always be composed of disk pages is
    memory allocated – (minus) memory limit

  2. Al says:

    I think there are an error with word connection, replace by contention

    Physical memory will be granted above the limit under normal conditions, but he limit will be enforced if contention occurs

    then c) has a lot of sense


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