fenzo-core/src/main/java/com/netflix/fenzo/TaskScheduler.java
public void enableVM(String hostname) throws IllegalStateException {
        logger.debug("Enabling VM " + hostname);
        assignableVMs.enableVM(hostname);
    }
public void enableVM(String hostname) throws IllegalStateException {
        logger.debug("Enabling VM " + hostname);
        assignableVMs.enableVM(hostname);
    }
Enable the VM with the specified host name. Hosts start in an enabled state, so you only need to call
this method if you have previously explicitly disabled the host.

@param hostname the name of the host to enable
@throws IllegalStateException if the scheduler is shutdown via the {@link #isShutdown} method.