Administration Guide › Managing Virtual Environments › VMware vSphere and vCenter Server › Resource Allocation › Resource Allocation Shares

Resource Allocation Shares

Shares specify the relative priority or importance of a virtual machine, resource pool, or vApp regarding to its siblings. If a virtual machine has twice as many shares of a resource as another competing virtual machine, it can consume twice as much of that resource.

Shares are typically specified as natural numbers. You can use defaults or assign a specific number of shares (proportional weight) to each virtual machine.

Specifying shares makes sense only with regard to sibling virtual machines, vApps, or resource pools. Sibling virtual machines or resource pools have the same parent in the hierarchy. Siblings share resources according to their relative share values, bounded by the reservation and limit. When you assign shares to a virtual machine, you always specify the priority for that virtual machine relative to other powered-on virtual machines.

For example, when competition occurs, a virtual machine with 2000 shares receives more CPU time than a virtual machine with 1000 shares. Shares are configured relative to the other shares; thus, only the proportion of shares matters, not the values of the shares. Three virtual machines with share values of 1000, 2000, 3000 act the same as three virtual machines with share values of 1, 2, 3. You can use any number scheme you prefer. If you leave ample space between the numbers, you can easier add resources to your resource pool in the future.

When there is no competition between resources, shares do not affect the operations of the virtual machines. Specifying shares help you to balance out your resource pools or vApps.