Shares specify the relative importance of a virtual machine within a virtual datacenter. If a virtual machine has twice as many shares of a resource as another virtual machine, it is entitled to consume twice as much of that resource when these two virtual machines are competing for resources.

Shares are typically specified as High, Normal, or Low and these values specify share values with a 4:2:1 ratio, respectively. You can also select Custom to assign a specific number of shares (which expresses a proportional weight) to each virtual machine.

When you assign shares to a virtual machine, you always specify the priority for that virtual machine relative to other powered-on virtual machines.

The following table shows the default CPU and memory share values for a virtual machine.

Table 1. Share Values
Setting CPU share values Memory share values
High 2000 shares per virtual CPU 20 shares per megabyte of configured virtual machine memory.
Normal 1000 shares per virtual CPU 10 shares per megabyte of configured virtual machine memory.
Low 500 shares per virtual CPU 5 shares per megabyte of configured virtual machine memory.

For example, a virtual machine with two virtual CPUs and 1GB RAM with CPU and memory shares set to Normal has 2x1000=2000 shares of CPU and 10x1024=10240 shares of memory.

The relative priority represented by each share changes when a new virtual machine is powered on. This affects all virtual machines in the same virtual datacenter.