VMware ESX Advance Features

I have to say, I still spend most of my time on ESX3.5 and ESX3.5i, since my old machines do not support the new released ESX4. Usually I use those ESX hosts as a standalone box to do my development. The features I used the most are snapshot, import and export OVF images, create template and clone machines. Even my ESX boxes do not have SAN, I still use vCenter to manage ESX hosts, since the template and clone are only available through vCenter. My structure actually looks like that:


All the standalone machines are managed by my vCenter, and each of those ESX host is operated by its own. The Virtual Machines can transferred from one host to another host, but we have to power off the virtual machines first.

Now I have a chance to access my friend's data center, then I can experience the new features which are listed on the VMware website.

1. VMotion:
I think all other features are based on this one more or less. VMotion enables the migration of running virtual machines from one physical server to another without
service interruption. It is obvious that my previous setting can migrate from one host to another ESX host, but the service has to be interrupted. It allows virtual
machines to move from a heavily loaded server to a lightly loaded one. The effect is a more efficient assignment of resources.


2. VMware DRS
Taking the VMotion capability one step further by adding an intelligent scheduler, VMware DRS enables the system administrator to set resource assignment policies that
reflect business needs and let VMware DRS do the calculation and automatically handle the detailed physical resource assignments. Now I am looking for the API to find out how to define the policy. If I know the API, I can define my own policy.


3. VMware HA
I probably mentioned this in previous post. VMware HA offers a simple and low cost high availability alternative to application clustering. It enables quick restart
of virtual machines on a different physical server within a Cluster automatically should the hosting server fail. The mechanism behind vmware HA, I think is: The agent keeps testing the heart beat of the machines, and make a clone of this machine periodically, but did not put it online. When the heart beat is lost, then powers up the latest cloned virtual machine, and powers off the original one.