Working with Slot Sizes and Admission Control

 

 

How to Use the Resource Allocation Tab to Determine Resource Use

  1. If the VMware vSphere Client is not already active, use the vSphere Client to log in.
  2. Go to Home > Inventory > Hosts and Clusters.
  3. Select Lab Cluster in the inventory and click the Resource Allocation tab.

 

 

 

How to Manage VMware HA Slot Size

The following steps will show you how to control slot allocation in a VMware HA cluster. The number of virtual machines that can be started in a cluster depends on how many slots are available.

  1. Select Lab Cluster in the inventory and click the Summary tab.
  2. View slot information for this cluster:
    1. In the VMware HA panel, click the Advanced Runtime Info link to view the slot information for this cluster.
    2. Click OK to dismiss the window.
  3. Set the CPU reservation on the virtual machine <name_of_your_machine>:
    1. Right-click <name_of_your_machine> in the inventory and select Edit Settings.
    2. Click the Resources tab.
    3. In CPU Reservation, type 512MHz.
    4. Click OK to commit the change.
  4. View slot information for this cluster:
    1. In the Summary tab of the cluster, click the Advanced Runtime Info link.
    2. Click OK to dismiss the window.
  5. Use the advanced VMware HA settings to enforce a slot size:
    1. Right-click Lab Cluster in the inventory and select Edit Settings.
    2. Select VMware HA from the list and click Advanced Options.
    3. In the Advanced Options (HA) window, enter the following option-value pair.
      1. Option: das.slotCpuInMHz
        Value: 300
    4. Click OK to close the Advanced Option (HA) window.
    5. Click OK to commit the changes.
  6. View slot information for this cluster:
    1. In the Summary tab of the cluster, click the Advanced Runtime Info link.
    2. Click OK to dismiss the window.
  7. Remove the advanced VMware HA setting:
    1. Right-click Lab Cluster in the inventory and select Edit Settings.
    2. Select VMware HA from the list and click Advanced Options.
    3. Select das.slotCpuInMHz and delete the entry.
    4. Click OK to close the Advanced Options (HA) window.
    5. Click OK to commit your changes.
  8. Remove the CPU reservation on your <your_machine_name>:
    1. Right-click <your_machine_name> in the inventory and select Edit Settings.
    2. Click the Resources tab.
    3. In CPU Reservation, type 0 (MHz).
    4. Click OK to commit the change.

 

 

 

 

How to Configure a VMware HA Cluster with Strict Admission Control
The following steps will show you how to assign enough  memory reservation to force Lab Cluster to have eight slots cluster-wide.

  1. Select Lab Cluster in the inventory and click Virtual Machines tab. Shut down all virtual machines.
  2. After all virtual machine are powered off, click the Resource Allocation tab.
  3. Identify the total memory capacity and divide it by the number of ESXi hosts in the cluster. The result is the usable memory per ESXi host. For example, if you have two ESXi hosts in your cluster and the total capacity for memory is 3,410MB, then 3,410 / 2 = 1,705.
  4. Assign memory reservations to virtual machines to configure four slots per ESXi host. For example, you will reserve 1,024MB of memory resources. That is, you will reserve 256MB for each of four virtual machines:
    1. Right-click each <your_machine_name> virtual machine listed in the Resource Allocation tab and select Edit Resource Settings.
    2. Type 256 (MB) for the memory reservation.
    3. Click OK to commit the changes.
  5. Right-click one <name> virtual machine and select Power > Power On.
  6. To see the effect that powering on this virtual had on your cluster, click the Lab Cluster Summary tab and click Advanced Runtime Info.
  7. Click OK to close window.
  8. Power on remaining <name> virtual machines. Click Advanced Runtime info to see the number of available slots change.

 

 

 

 

 

How to Configure a VMware HA cluster with Flexible Admission Control
The following steps will show you how to reconfigure your cluster flexible admission control.

  1. Right-click Lab Cluster in the inventory and select Edit Settings.
  2. Select VMware HA from the list.
  3. Set Admission Control Policy to Percentage of cluster resources reserved as failover spare capacity and 25%.
  4. Click OK to accept your changes.
  5. Click the Resource Allocation tab.
  6. Click the Memory button to enter Memory view.
  7. Remove the virtual machine memory reservation for each <name> virtual machine:
    1. Click the Reservation – MB column heading. This will sort the memory reservations numerically.
    2. Select a virtual machine that has a memory reservation.
    3. Select the memory reservation value (for example, 256) and type 0. Press Enter.
    4. Select another virtual machine. Remove the reservations as you did in the previous step.
  8. Edit the settings of the cluster to allow the number of running virtual machines to exceed the failover capacity of the cluster:
    1. Right-click the cluster name and select Edit Settings.
    2. In the left pane, select VMware HA.
    3. In the Admission Control panel, select Disable: Power on VMs that violate availability constraints.
    4. Click OK to commit your changes.