ESXi hosts without swap enabled cannot be added to a VMware High Availability Cluster

Products

• VMware vCenter Server
• VMware vSphere ESXi

Issue/Introduction

• ESXi hosts that do not have swap enabled cannot be added to a VMware High Availability (HA) cluster.
• You may see the error:
  
  cmd addnode failed for primary node: Internal AAM Error - agent could not start

Environment

VMware vCenter Server 4.0.x
VMware ESXi 4.0.x Embedded
VMware ESXi 3.5.x Installable
VMware VirtualCenter 2.5.x
VMware ESXi 3.5.x Embedded
VMware ESXi 4.1.x Installable
VMware ESXi 4.0.x Installable
VMware vCenter Server 4.1.x
VMware ESXi 4.1.x Embedded

Resolution

Starting with VirtualCenter 2.5 Update 1, only ESXi systems with swap enabled can be added to an HA cluster. ESXi systems with swap not enabled cannot be added to HA clusters, and display an error message similar to the following:

An error occurred during configuration of the HA agent of the host.

The Tasks & Events page of such a ESXi system describes the error with a description similar to the following:

HA agent has an error : Host in HA Cluster must have userworld swap enabled

To enable swap on your ESXi host system:

1. On the VirtualCenter Server, select the ESXi host.
2. Click the Configuration tab.
3. Click Advanced Settings.
4. Choose ScratchConfig.

5. Configure ScratchConfig.ConfiguredScratchLocation to a valid directory with sufficient space (1GB) to hold the userworld swap file. The userworld swap can be configured on local storage or shared storage.

   Note: Each swapfile needs a unique name across all ESX hosts. The path must exist before changing the scratchconfig setting. You can create this directory with the datastore browser.
   
   For example, /vmfs/volumes/<DatastoreName>.
   
   

6. Select the ScratchConfig.ConfiguredSwapState option.
7. Click OK.
8. Reboot the ESXi system.

After you have enabled swap on the ESXi host system, you can add the host to a VMware HA cluster.

Note: This solution also applies for Update 2.