SanDisk unveiled a prototype of its Vaulter Disk drive, a solid state PCIe module that attaches to and complements the standard hard drive.
An excerpt from IDM:
SanDisk's 8 to 16 GB cards on the other hand, have enough capacity to hold an operating system, quite a few programs and a chunk of frequently-accessed data.
As with all SSDs, this will no doubt see system performance and battery life increase, however, as it does not do away with the sheer capacity of magnetic storage the solution is offering the best of both worlds.
Magnetic hard drives have the advantage of lowest cost-per-gigabyte, while solid state-based drives have the advantage of rapid innovation in speed and size. The Vaulter Disk works with standard hard drives to speed up boot time and launch the OS and selected applications.
SanDisk vaults over hard drive limitations (NetworkWorld)