9/14/09:
By Tony Lavia, President & CEO, Flexstar Technology
New Technology must be at least ten times better than the existing on in order to displace it.
Everyone has heard of Moore’s Law, but what about Grove’s Law: that a new technology must be at least ten times better than the existing one in order to displace it? Are Solid State Drives (SSDs) on the way to becoming the next technology leap-ahead in the computer industry?
An SSD is a solid state storage device that employs the same interfaces and form factors as Hard Disk Drives (HDDs). The storage medium is non-volatile, utilizing integrated circuits in place of rotating magnetic or optical media.
The vast majority of today’s SSDs are based on Flash (specifically, NAND) chips, a microprocessor-based controller, and software that integrates these components into a peripheral storage system which mimics a HDD. Compared to a HDD it provides high access speed by eliminating mechanical movement such as head seeks and platter rotation.
So what makes the SSD better? Does it achieve a 10X improvement? The benefits offered are derived from the elimination of all things mechanical: the spindle, the platters, the heads, the actuator and the actuator arm.
There is also the tantalizing prospect of jumping on to the semiconductor power curve (Moore’s Law) for accelerated evolution. (Note that, whereas the capacity of HDDs has increased rapidly over the years, the data transfer speed has not kept up, now lagging behind the ability of motherboards to keep the drives busy.)
The solid state nature of SSDs make them particularly suitable for harsh environments, rugged applications (vibrations can play havoc with the microscopically small gap between the recording head and the platter of a HDD), applications requiring massively higher levels of IOPS (for random, mostly “read” operations) and products where form and function trump the added cost.
The biggest impediment to adoption of SSDs at a “replacement” pace is their cost. Measured as dollar/GB, a SSD is priced at 10 to 20 times that of HDD storage. This is not to say that cost represents a barrier, or that there has not been progress in this area– rapid progress, at that.
Also, in the areas of capacity and performance, SSDs used to max out at 32GB, with transfer speeds barely equal to the slowest hard drives. The progress in two years has been astounding: SSDs are now available with 512GB – with data transfer speeds surpassing even the fastest, short-stroked hard drives - at a fraction of their original cost.
Hard drives have also progressed along their own “power curve:” capacity. It is not uncommon to see 1.5TB drives selling in the sub $200 range. That’s about $0.13/GB, about 20 times less expensive than corresponding SSDs.
There is still a ways to go before SSD technology will do to HDDs what HDD technology did to tape storage. Nevertheless, there are currently important niches where SSDs can already be cost-justified, such as for (1) enterprise applications involving intensive random IO – here, SSDs leverage other parameters in the Total Cost of Ownership (TCO) equation (such as IOPS, power efficiency, density, cooling ); and (2) for applications where the size or durability provides innate product value that could not be achieved with a corresponding, albeit cheaper, HDD.
In the data center environment, for most situations, capacity will continue to trump performance as the determinant of overall TCO. The conventional view is that SSDs will seep gradually onto the scene as a complementary layer in the storage “stack”, taking their place at the pinnacle of the fast/faster/fastest layers of storage technologies. It’s a lofty position, but a limited one: HDDs and tape storage comprise the bulk of the requirements. This is “improvement” - but it is not “replacement”, in the context of Grove’s Law.
However, there are a few wild cards that may change the game:
1. On the technology front, many of the limitations and costs are due to the memory technology itself, i.e. NAND memory chips. New and promising alternative technologies are being developed (e.g. FRAM, PCM, MRAM), which could change the cost/benefit equation in a single stroke. Indeed, developments in NAND itself, in the form of MLC (Multi Level Cell) silicon, may break through the cost entry barrier.
2. On the computer system front, the natural advantages of solid state storage are being held back by systems architectures which have been built to assume and work around the lags and delays of the hunt-and-peck inefficiencies of mechanical storage. By re-vectoring operating systems so as to harness the performance attributes of SSDs, it may be possible to dramatically improve on some of the computer characteristics that irk users beyond proportion.
3. Capacity for capacity’s sake will, for most applications, eventually reach a point where enough is enough. For example, take the case of a business notebook. Usage studies have shown that, even for a road warrior, 64GB of storage is normally sufficient. Let’s double it to 128GB for some extra margin. If a user can see real benefits (such as instant startup), it is unlikely that a $200 premium, even at today’s prices, would represent any kind of barrier, especially to this sector of the market. As another example, in 2007 Apple decided that 16GB was plenty enough storage for the music applications in the original Ipod – the benefits relating to size and form trumped out the lower cost and extra capacity of the HDD.
4. Cloud computing - spurred on by Netbooks, web-optimized operating systems (e.g. Android), near-laptop capable PDAs, and ASP services rewards performance over storage in the PC by relegating mass storage into the cloud. The key value parameter shifts to performance/dollar from capacity/dollar.
5. The supply chain infrastructure for the SSD could evolve into a more efficient eco-system with inherently lower cost structures and greater ability to optimize for focused applications and environments.
Let’s briefly look at one aspect of (5) above, in the area of industry standardization. Today, the HDD industry has developed a sophisticated system of testing, for every phase of development and production: DVT, EVT, RDT, out-of-the-box testing, production testing, QA testing, Qualification, etc. The bad news: there is no process standardization – everyone does their own thing. The attendant costs of these systemic inefficiencies percolate, of course, on down to the end user.
The nature of SSD technology cries out for simplified and standardized operational testing among the various players. A hard drive is composed of many and varied components. They can behave differently depending on the operational environment.
NEXT >
|
