Nikkei Electronics Asia -- June 2009

[Feature] SSDs Challenge HDDs, but Quality a Problem [Part 2]

Continued from SSDs Challenge HDDs, but Quality a Problem [Part 1]

Explosive Growth in PCs

SSDs are finding use in more than data centers, server systems, disk arrays and similar infrastructural applications. 

It is likely that SSDs will spread explosively in notebook personal computers (PC) in the next year or two. PC manufacturers are especially interested in SSDs for business-use notebooks. "Compared to home-use notebook PCs, business models are carried around much more often, and that means they are often subjected to unexpected impacts.

The most important thing is to protect the user's data, and SSDs are the best way to do that," explains Yosuke Konaka, manager, Ultra Portable Department, Personal Computing Division, Personal System Business Unit of Fujitsu, Ltd of Japan. In fact, even if a notebook PC with an SSD falls, he adds, "Storage device-related failures are extremely uncommon."

Another point is that business products do not require as much storage capacity as home-use systems, for reasons of preventing data leaks. This is another reason why SSDs are becoming so popular.

The market for SSD-equipped notebook PCs has already taken off, with notebook PCs featuring 100-Gbyte-class SSD storage capacity appearing at the end of 2008 (Fig 5). There were a few notebook PCs with SSDs even earlier, but most were low-end machines selling for about Yen50,000 (so-called "netbooks"), with storage capacities of no more than 32 Gbytes.

SSD Prices Keep Falling

One factor contributing to the adoption of SSDs in notebook PCs is the steady drop in prices of NAND Flash memory, which is said to account for about 80% of SSD cost.

As of Mar 2009, NAND Flash memory costs about US$1.25 per GB capacity (Fig 6). This is about 3.3 times the cost of a 2.5-inch HDD (160GB) in terms of cost per GB. If NAND Flash memory were used to make an SSD with the same 160GB capacity, it would go for about US$250, or at least four times the cost of the HDD. Given the price difference, it's not surprising that SSDs are limited to only a few notebook PC models.

The situation seems likely to change soon, though: the prevailing opinion is that SSD prices will continue to drop at about the current rate for the next two years, if not longer.

Assuming the price per GB continues to drop at 50% annually for NAND Flash memory, it will hit about US$0.60 in Mar 2010, making possible a 100-Gbyte SSD for about US$75.00. In Mar 2011 the per-GB price of NAND Flash memory will drop to about US$0.30, working out to a 200GB SSD for the same US$75.00. The technical problems have been overcome for both of these designs already.

If the competition between memory manufacturers intensifies and prices erode faster than 50% annually, the price of 1GB of NAND Flash memory could reach US$0.15 in Mar 2012, leading to a 400GB SSD for US$75.00. This would be less than half the price of a 2.5-inch HDD in the same capacity range; and if that were to happen, it wouldn't be at all surprising to see most PCs sporting SSDs instead of HDDs in 2012.

Next Up: Optical Discs?

The price level of US$0.15/GB thought possible for NAND Flash memory in Mar 2012 could open up another giant market, too: replacements for digital videodisc (DVD), Blu-ray Disc and other optical discs.

If NAND Flash memory does drop to US$0.15/GB, a 25GB capacity (equivalent to that of Blu-ray Disc) could be achieved for US$3.75, which is about the same as the current cost of Blu-ray Disc media. In fact, a comparison simply by price per GB puts the price of NAND Flash memory below that of even DVDs. A source at Toshiba comments, "The next step after HDDs is of course optical discs. We're working on multi-level technology now to accomplish this."

Ken Takeuchi, PhD, Associate Professor, Department of Electrical Engineering & Information Systems, University of Tokyo, adds, "I wouldn't be surprised to see projects aiming for multi-level technologies for 5 bits/cell, or higher, in preparation for replacement of optical discs."

HDD Makers Turn to SSDs

SSDs are gradually becoming more important in markets that have seen the fiercest HDD competition in the past, and HDD manufacturers are beginning to change their strategies accordingly. Major manufacturers are announcing plans to develop and supply their own SSDs.

In Mar 2009 Western Digital Corp of the US, the number two player in the HDD industry, made its move by acquiring SSD manufacturer SiliconSystems Inc of the US, promptly announcing its entry into the SSD market. A source at Western Digital explained, "We plan to aggressively develop SSDs for a wide range of applications including core servers and other corporate infrastructure, notebook PCs and netbooks."

In Nov 2008, a few months before Western Digital's announcement, Hitachi Global Storage Technologies (HGST) of the US announced a tie-up with Intel Corp of the US to develop SSDs for servers. They plan to develop SSDs with a high-speed interface (like SAS or Fibre Channel) and ship in 2010. The NAND Flash memory, controller integrated circuits (IC), etc, used in the SSDs will be developed by Intel. According to Hiroshi Deki, senior manager, Product Planning & Strategic Marketing, Consumer & Commercial HDD, Business Group at HGST, "We've received a large number of requests for SSDs, and decided to get into the market. When it comes to enterprise-class storage devices, each customer has detailed and different needs. We've worked with them all through our HDD business, and already know how to support them and provide the other services needed. We're confident we can succeed in the SSD business, too."

It is expected that HDD manufacturers will bring a variety of technical expertise to SSDs in the future, and that will probably stimulate further SSD technology evolution.

To be continued

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