You shouldn’t have to reboot your ESX servers very often. But when you do, you might want the virtual machines to start up automatically. To configure a virtual machine to start up (or shut down) automatically select the host and click on the Configuration tab.
Then click on virtual machine Startup/Shutdown and click on Properties, selecting “Allow virtual machines to start and stop automatically with the system”. As I mentioned in a previous article, you can also configure the operating system to start after a brief delay by providing a Default Startup Delay time, allowing time for booting systems to run scripts or to throw them into Safe Mode. You can also configure automated shutdown options at this screen as well.
Also use the Move Up and Move Down options to indicate what order virtual machines start when the system starts. Click Save and the configs are written to the system.