Integrating a solution with ESX Agent Manager has several benefits and eliminates potential problems that can occur when you deploy ESX agent virtual machines.

Monitoring solutions

When you integrate a solution with ESX Agent Manager, users can monitor the health of agent virtual machines in the vSphere Client. The solution can monitor ESX agents by using the ESX Agent Manager API. Integrating a solution with ESX Agent Manager also helps you to add functions to ESXi hosts.

User privileges

By integrating a solution with ESX Agent Manager, you can limit certain operations on ESX agent virtual machines to certain types of user. For example, you can block all users from powering off an ESX agent unless they have the EAM.Modify privilege.

Integration with vSphere features

When you develop solutions that deploy virtual machines that extend the function of ESXi hosts, integrate the solution with ESX Agent Manager. If you do not integrate the solution and ESX Agent Manager, vSphere does not detect that virtual machines are ESX agent virtual machines, Virtual machines that ESX Agent Manager deploys integrate with vSphere features in ways that other virtual machines do not. For example, if an ESXi host implements vSphere High Availability (VMware HA) and that host stops running unexpectedly, normally all the virtual machines running on that host migrate to another ESXi host. An ESX agent virtual machine should not migrate to another host. Features such as vSphere Distributed Resource Scheduler (DRS), the Add Host to Cluster operation, vSphere Distributed Power Management (DPM), and maintenance mode can also create problems if they modify or migrate ESX agents. Similarly, if one of these features migrates or modifies an ESX agent that a solution requires, that solution can stop running.

ESX Agent Manager is compatible with the VMware HA, DRS, AddHost, DPM, and maintenance mode features. By integrating a solution with ESX Agent Manager, you can deploy ESX agent virtual machines that modify the function of ESXi hosts and implement VMware HA, DRS, AddHost, DPM, and maintenance mode. ESX Agent Manager ensures that solutions that deploy ESX agents integrate correctly with these vSphere features.

ESX Agent virtual machines and High Availability

If you have a configuration with a very large virtual appliance per host, a best practice is to use an ESX Agent VM as a container for the appliance, because vCenter Server High Availability (HA) feature gives special priority to ESX Agent VMs.

The HA feature will power on an ESX Agent VM before any other VMs.

If a failover host policy is in use, the HA feature allows Agent VMs to be powered on with the failover hosts.

The HA feature does not include ESX Agent VMs in admission control calculations. Therefore, if you want to use a VM that is not included in the slot size for the 'host failures to tolerate' admission control policy, you can use an Agent VM.

To take advantage of these special priorities, you must include an ESX Agent VM on each host in a cluster.

Table 1. Interaction between vSphere features and ESX Agent Manager
vSphere Feature Interaction with ESX Agent Manager
VMware HA
  • If a host stops unexpectedly, VMware HA does not start an ESX agent virtual machine on another host, unless a failover policy is in use.
  • When a host restarts, VMware HA restarts the ESX agent virtual machines before it restarts other virtual machines.
  • ESX agent virtual machines are not included in slot size for admission control calculations.
Distributed Resource Scheduler (DRS)
  • ESX Agent Manager pins ESX agent virtual machines to the hosts on which they are running. DRS does not move ESX agent virtual machines between hosts in a cluster.
  • ESX Agent Manager blocks DRS from moving virtual machines that are not ESX agents to hosts in clusters where ESX agents that the virtual machines require are not available.
Add Host to Cluster operation When a user adds a host to a cluster of hosts that require an ESX agent, ESX Agent Manager deploys the required ESX agents on the new host.
vSphere Distributed Power Management (DPM) DPM can put a host into standby mode even when ESX agent virtual machines are present. DPM powers off ESX agent virtual machines only after it has moved all the other virtual machines to another host and put the host into standby mode.
Maintenance mode When a host enters maintenance mode, ESX Agent Manager powers off any ESX agent virtual machines and restarts the ESX agents when the host exits maintenance mode.