In the Advanced settings, you can configure the resource allocation settings (shares, reservation, and limit) to determine the amount of CPU, memory, and storage resources provided for a virtual machine.

Use the resource allocation settings (shares, reservation, and limit) to determine the amount of CPU, memory, and storage resources provided for a virtual machine.

Resource Allocation Shares
Shares specify the relative importance of a virtual machine within a virtual data center. 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.
Resource Allocation Reservation
Specifies the guaranteed minimum allocation for a virtual machine. VMware Cloud Director allows you to power on a virtual machine only if there are enough unreserved resources to satisfy the reservation of the virtual machine. The virtual data center guarantees that amount even when its resources are heavily loaded. The reservation is expressed in concrete units (megahertz or megabytes).

For example, assume that you have 2 GHz available and specify a resource allocation reservation of 1 GHz for virtual machine 1 and 1 GHz for virtual machine 2. Now each virtual machine is guaranteed to get 1 GHz if it needs it. However, if virtual machine 1 is using only 500 MHz, virtual machine 2 can use 1.5 GHz.

Reservation defaults to 0. You can specify a reservation if you need to guarantee that the minimum required amounts of CPU or memory are always available to the virtual machine.

Resource Allocation Limit
Specifies an upper bound for CPU and memory resources that can be allocated to a virtual machine. A virtual data center 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 or megabytes).

CPU and memory 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.

In most cases, it is not necessary to specify a limit. You might waste idle resources if you specify a limit. The system does not allow a virtual machine to use more resources than the limit, even when the system is underutilized, and idle resources are available. Specify a limit only if you have good reasons for doing so.

Prerequisites

  • A reservation pool virtual data center.
  • Ensure that a certain amount of memory for a virtual machine is provided by the virtual data center.
  • Guarantee that a particular virtual machine is always allocated a higher percentage of the virtual data center resources than other virtual machines.
  • Set an upper bound on the resources that can be allocated to a virtual machine.

Procedure

  1. On the Virtual Data Center dashboard screen, click the card of the virtual data center you want to explore and from the left panel, select Virtual Machines.
  2. Click Card Icon to view the list in a card view and, optionally, arrange the list of virtual machines from the Sort by drop-down menu.
  3. In the card of the virtual machine you want to edit, click Details.
  4. Click Advanced and Edit.
  5. Set the resource allocations shares for the CPU settings by selecting an option from the Priority drop-down menu.
    Option Description
    Low Allocates 500 shares per virtual CPU.
    Normal Allocates 1000 shares per virtual CPU.
    High Allocates 2000 shares per virtual CPU.
    Custom Allows you to assign a specific number of shares by entering the 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.

  6. Specify the reservation for the CPU settings by entering the reservation in MHz, and optionally, the limit for the CPU settings in MHz.
    Option Description
    Unlimited The default CPU resource option.
    Maximum Specify an upper bound for CPU resources that can be allocated to a virtual machine in MHz.
  7. Set the resource allocations shares for the memory settings by selecting an option from the Priority drop-down menu.
    Option Description
    Low Allocates 5 shares per megabyte of configured virtual machine memory.
    Normal Allocates 10 shares per megabyte of configured virtual machine memory.
    High Allocates 20 shares per megabyte of configured virtual machine memory.
    Custom Allows you to assign a specific number of shares by entering the number of shares.
  8. Specify the reservation for the memory settings in MB and, optionally, the limit for the memory settings in MB.
    Option Description
    Unlimited The default memory resource option.
    Maximum Specify an upper bound for memory reservation that can be allocated to a virtual machine.
  9. Click Save.