Product documentation
XenCenter
2024 8.2.7
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VM Group

September 26, 2024
Contributed by: 
X

Note:

This feature is available in XenServer 8 and later pools. It is not available in pools running Citrix Hypervisro 8.2 Cumulative Update 1.

You can assign your VMs to VM groups that are started on hosts in your pool according to the placement rules of the group. The available placement types are “anti-affinity” and “normal”.

VM groups with normal placement do not have any special behavior.

VM groups with anti-affinity placement have the following rules:

  1. No single host is the only place all VMs in a particular group are running.
  2. The count of VMs within the group for each host is as even as possible.

When a VM in a VM group with anti-affinity placement rules is started or evacuated from a host, XenServer chooses to place the VM on a host that enables the VM group to follow these anti-affinity placement rules as closely as possible. If the VM start or host evacuate cannot be done without breaching the placement rules, XenServer prioritizes completing the action over following the placement rules.

If the anti-affinity rules are breached, you receive an alert. Alerts are generated if all the running VMs in an anti-affinity group reside on a single host. If this changes, the alert is cleared. This alert is not generated if only one of the VMs in the group is running or no VMs in the group are running. For more information, see XenCenter Alerts.

In the following scenarios the VM group placement rules do not take effect:

  • In pools with Workload Balancing (WLB) enabled, the VM group is not used for starting, restarting, resuming, or migrating the VM. Instead, Workload Balancing nominates the best server for the VM by analyzing XenServer resource pool metrics and by recommending optimizations. These recommendations can cause the VM anti-affinity rules to be breached.
  • If the VM has a home server defined, this setting takes priority over the VM group setting.

Considerations when using VM groups:

  • Only 5 anti-affinity groups per pool are supported.
  • When you clone a VM that is in a VM group, the new VM is not added to the same VM group. You must explicitly set the VM group for the new VM.
  • If you revert a VM to a previous snapshot, the VM retains its current VM group setting. This setting does not change to the value it had when you took the snapshot.
  • Exporting a VM does not retain the VM group setting. If you import this VM again, it is not added to a VM group. You must explicitly set the VM group for the imported VM.

In the New VM wizard on the VM group tab, you can select the VM group to add the VM to. This tab also gives the option to create a new group. You can add a VM to only one VM group.

After VM creation, you can change a VM’s group in one of the following places:

  • In the Resources pane of XenCenter, you can right-click on a VM and choose Assign to VM group. The submenu shows the available VM groups and also gives you the option to create a new VM group. The current VM group for the VM is marked with a check.
  • In the Resources pane of XenCenter, you can right-click on the pool and choose Manage VM groups. For more information, see Manage VM groups.
  • In the XenCenter main menu, you can select VM > Assign to VM group. The submenu shows the available VM groups and also gives you the option to create a new VM group. The current VM group for the VM is marked with a check.
  • In the XenCenter main menu, you can select Pool > Manage VM groups. For more information, see Manage VM groups.

You can manage your VM groups in XenCenter by using the Manage VM group dialog box. For more information, see Manage VM groups.

XenServer 8

VM Group
September 26, 2024
Contributed by: 
X
September 26, 2024
Contributed by: 
X

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