Media coverage of the storage industry often concentrates on the perceived fight for market dominance between Hard Disk Drives (HDDs) and NAND-type flash memory.

That certainly seemed to be the case one year ago, when Apple Computer Inc.'s introduction of a NAND-flash-based version of its audio iPod appeared to deal a heavy blow to the market for the 1-inch HDD, which had been used in previous iPod models.

However, the HDD industry survived this, and rebounded by selling a larger form-factor product for Apple's iPod video: the 1.8-inch hard drive. Now, the number of HDD suppliers planning to introduce 1.8-inch drives for the consumer electronics segment is rising, with the total now at six, up from two previously.

One year later, the talk is not so much about competition between HDDs and flash, but of cooperation and coexistence. The key areas of hybrid HDDs and Intel Corp.'s Robson concept are major areas where flash is making a dent in the computing space. Both Microsoft Corp. and Intel have announced initiatives to use NAND flash memory to reduce the mechanical latency inherent in HDDs. As a first step, this is targeted for the notebook PC platform. It is estimated that the flash capacities will be in the range of 256Mbytes to 512Mbytes.

Microsoft's Vista Operating System initiative calls for an ultimate hybrid HDD wherein NAND flash will act as the main cache between the operating system and the rotating hard drive — an approach called ReadyDrive. Intel's Robson initiative, on the other hand, places this NAND flash function in a separate module closer to the microprocessor and installed on the motherboard.

Both initiatives attempt to reduce the latency of HDDs and diminish their duty cycles, which in turn help to cut power consumption and incidences of operational drop shock.

Both initiatives are slated for early 2007, and although they appear to be cooperative, some overlapping functions might exist. Meanwhile, four industries are involved in these initiatives: the HDD makers, the flash suppliers, the motherboard manufacturers and the PC OEMs. These overlaps, plus the involvement of so many industries, make for a great deal of complexity. Implications of HDD/flash storage

From the HDD industry perspective, key factors of such storage systems include the cost of the additional flash module in a hybrid hard drive, the testing of such systems and the carrying of multiple SKUs. Furthermore, this has implications for the type of HDD used, including, capacity, spin speeds, form factor and interfaces. Both Vista and Robson call for SATA interfaces.

From the point of view of the PC industry, placing flash either on a motherboard or on a hybrid HDD represents added cost. Furthermore, the notebook PC industry also has to conduct system-level testing and carry additional SKUs where necessary.

Benefits of HDD/flash storage

From an end-user perspective, there are significant advantages of flash/HDD schemes, including fast boot up, quicker application loading and speedier recovery from HDD sleep mode. These result in longer battery life, lower incidences of drop shock — resulting in lower chances of lost data — and an overall faster performance of the system.

Questions regarding HDD/flash storage systems Despite these advantages, several questions have arisen regarding flash/HDD systems — questions that may determine their degree of success. These include:

*How much are users willing to pay for the added advantage of faster times for boot up and application loading?

*Will PC OEMs simultaneously design systems with hybrid HDDs and Robson, thus putting flash in two places at once on their computers?

*Which of the three possible variations produces the best results: hybrid HDDs plus Robson, regular HDDs plus Robson or hybrid HDDs without Robson?

Furthermore, Microsoft Vista needs a removable USB flash drive for its ReadyBoot feature. At IDF, Intel demonstrated a doubling in performance when loading applications using a notebook PC that utilized both Vista and Robson. Intel in the first half of 2007 plans to introduce Robson in its upcoming Santa Rosa platform, which represents the next generation of its Centrino microprocessor for mobile PCs.

Microsoft's Vista rollout is expected in the first quarter of 2007. iSuppli has made a preliminary estimate of notebook PC shipments with Robson and hybrid HDD drive penetration, and we show an even mix of both systems by 2010.

The presence of NAND flash in mobile PCs offers a high value proposition for end users. However, challenges remain for PC OEMs in terms of the selection of the right design and components, since there are two competing but coexisting technologies arriving almost simultaneously. iSuppli expects the design and component selection issues to be sorted out by the middle of next year.