With Ultrabooks becoming rapidly more popular also the quest for thinner and smaller hardware has started. We've seen most innovation on the storage part, SSDs and HDDs have decreased in size tremendously the last years. Today WD announced that it has made another breakthrough on decreasing HDD size and is currently sampling 5mm thin hybrid disks. These 'hybrid' disks combine the best of HDDs and SSDs, they use fast but expensive SSD storage (MLC NAND in this case) for caching frequently used files and cheap but slower HDD storage for infrequently used files.
Before, 7 mm disks were often seen in Ultrabooks, in laptops manufacturers usually used 9.5 mm thick drives. WD hasn't announced any details yet, other than that the HDD will have at least 500GB of space. It's unclear how much of it will be SSD (NAND flash memory) and how much will be HDD (traditional magnetic storage).
