If you happen to encounter a situation in which you cannot start from the Recovery HD, such as your hard drive stopped responding or you installed a new hard drive without Mac OS X installed, new Mac models introduced after public availability of OS X Lion automatically use the Lion Internet Recovery feature if the Recovery HD (Command-R method above) doesn't work. Lion Internet Recovery lets you start your Mac directly from Apple's Servers. The system runs a quick test of your memory and hard drive to ensure there are no hardware issues.