For a decade or more, solid state disks (SSD) have been like Ferrari Enzos: distant, exotic, sublimely fast, and very, very expensive.

Yes, we drivers of Fords, BMWs and Mercedes would like one but, well, get real. So only military and government organisations needing to put utterly reliable and very fast storage in fighter planes and reconnaissance satellites, or intelligence agency eavesdropping systems, or the high-end reaches of financial trading corporations have used SSDs.

They have been built out of computer memory chips, DRAM, and are wickedly fast having none of the head-moving latency of a spinning hard drive. But now there is a flashy new kid on the block, a flash memory-based SSD technology. It is still faster than a hard drive but slower than DRAM, but it is also much less expensive than DRAM. The relatively cheap chips found in memory sticks can be built into an SSD and used to store and access tens and hundreds of gigabytes of data.

What Texas Memory Systems, a successful supplier of RamSan DRAM SSDs, has done, is to build a kind of hybrid SSD, one with bulk storage based on flash memory chips and a front-end cache using DRAM, the RamSan 500. It is available with capacities beyond 1TB, is much faster than a terabyte hard drive and its price occupies a mid-point between hard drives and DRAM SSDs.

We talked with Woody Hutsell, an executive VP at TMS, about the RamSan 500.

Techworld: How has your market responded to the RamSan 500?

WH:Since we announced the RamSan 500 with its cached flash around 50 percent of the RFPs coming in refer to it. There are lots of leads in data warehousing, seismic processing and similar sectors. Some have committed. We're not shipping yet. The first units will go out in December.

Customers in the finance and telecoms area are taking it. There is some overlap in customer sets for DRAM and flash RamSan but flash RamSan gets us to new customers.

We're talking to one of the (financial) exchanges. Before it would have been a DRAM customer. It will probably be both a DRAM and flash customer in the future.

Techworld: Could you position SSDs and HDDs in a green sense please?

WH:A 2TB RamSan 500 uses 250 watts. A 72GB hard drive would need twice that power. Add in the RAID controller and you're looking at twenty times less power usage with the SSD. Greg Schultz of Storage IO has written a paper on this, on looking at performance per watt.

Techworld: How is the RamSan 500 priced?

WH:It's not cheap; it's an enterprise storage device costing around $300,000 - $340,000 for a 2TB unit. But the DRAM-based RamSan would cost around $1.5 million for a 2TB unit.

Techworld: Could you describe how the flash SSD might be used?

WH:In a write-intensive environment DBMS reading lags are small, only a few gigabytes are involved, so a DRAM solution is okay. Flash DRAM is high capacity and can be used in different applications. All our customers tier. Transaction logs would be on tier zero (SSD) along with database table space. The bulk primary data will be on disk. This is ILM (information lifecycle management) at a basic level.

In most cases we're still looking at application-centric storage uses for SSDs. If the SSD is to transition to general tier zero use then you need some automation to place files and data on the right storage tiers at SAN and array levels.

This decision layer adds latency. If the decision is slow then you've invalidated the decision to buy SSD technology.

Techworld: What's your view of the SSD market's growth? What will drive array vendors do?

WH:From 2005 to 2006 there was an 80 percent growth in SSD sales. It was 30-40 percent from 2006 to 2007. From 2007 to 2008 it could be 100 percent; largely as a result of flash SSD systems. I think the market will change rapidly. I think most of the major RAID HDD array vendors will put flash in their controllers.

Using flash SSD technology is an easy route to increased performance. How do they do this? Do they take the easy route and just modify firmware? Or do they modify the architecture to take more advantage of SSD?

TMS would be open to OEM deals for this.

Overall, we're in a really good position today. We have the only product with enterprise-level controls. It's going to be a very exciting time in the market.

Techworld comment

Adding a DRAM cache to flash SSD has enabled quite high-performance at a fifth of DRAM SSD prices. The hard drive array vendors will all see the opportunity to front-end their HDD-based arrays with SSD technology and so provide a faster-than-disk new storage tier, tier zero.

There will be two main supply sources for this: incoming flash SSD suppliers such as Micron and STEC; and existing SSD suppliers such as TMS. The trick will be, returning to the car analogy, judging how to add a supercar performance boost to your middle-of-the-road saloon (sedan). Do you add BMW technology to a Ford Focus, or Ferrari technology to a BMW ?

There is a longer-term decision to be made too. Will SSD prices drop enough to cause wholesale replacement of fast hard drives in datacentres? If they do then Symmetrix-level array sales face decimation unless they adopt the technology so that tier one storage migrates to SSD. This is not a fantastical idea. Look out for the forthcoming interview with Joseph Reger, the chief technical officer for Fujitsu Siemens Computers.