Managing server placement groups

Server placement groups provide you control over the host or server on which a new virtual machine (VM) is placed. By using server placement groups, you can build high availability within a data center.

You can apply an affinity or anti-affinity policy to each VM instance within a server placement group. After you create a placement group, you can provision a new VM instance in the placement group. When you set a placement group with an affinity policy, all VMs in that placement group are launched on the same server. When you set a placement group with an anti-affinity policy, all VMs in that placement group are launched on different servers.

You can use the Add Server to Placement Group API to add VM to a placement group.

Creating server placement groups

You can create server placement groups and provision VMs in this placement group. The VMs in this group can be set to have affinity or anti-affinity policy with each other. Each placement group that you create must have a unique name. You can create a maximum of 25 placement groups. If you need to create more than 25 placement groups, raise a support ticket to increase the maximum limit. Use the following API to create a placement group: Create a server placement group.

You cannot change the policy or name of a placement group after it is created. You can only add or remove VMs within the placement group.

To create a new placement group, complete the following steps:

Go to the Power Virtual Server user interface and click Server placement groups.
In the Server placement groups page, click Create group.
Specify a name for the new placement group. Select a colocation policy to specify whether all the VMs under this placement group must reside in the same server or in a different server.
Click Create.

In the Server placement groups page, the table displays all placement groups for this Power Virtual Server instance. The table also indicates the number of VMs in each group and also the colocation policy.

Server Placement group APIs

You can use the following for managing server placement groups:

Get all server placement groups: Displays all existing server placement groups.
Get server placement group detail: Displays details about a specific server placement group.
Delete server placement group: Deletes server placement groups even if they contain member instances.
Remove server from placement group: Removes a server from a server placement group.

Add VMs to a server placement group

You can add VMs to a server placement group. The VMs that you add to the server placement group must be in an Active state. You cannot add a VM to a server placement group that contains a VM that is in Build state. In this case, after you create a VM you must wait for the VM to be in Active state and then add another VM in the server placement group. Use the following API to add a server to a placement group: Add server to placement group.

When you add a VM to the server placement group, the request might not be complete due to a conflict (409) with the affinity policy of the server placement group. In this case, you might need to open a DLPAR operations support ticket. To open a support ticket, see Getting help and support.

To add a VM to a placement group, complete the following steps:

Go to the Power Virtual Server user interface and click Server placement groups.
In the Server placement groups page, from the placement group table select a placement group name that you want to add the VM.
In the VMs in placement groups section, you can create a new VM and add it to the placement group. You can also add an existing VM to the placement group.
Click Add existing VM to add an existing VM to the placement group. Select one or more VMs from the table and add it to the placement group.

VMs that you select must be on the same server or different server depending on the colocation policy of the placement group. A VM can belong to only one placement group and VMs that are already placed in a different placement group is disabled in the table.