Has the time come for solid state discs?

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Has the time come for solid state discs?

IBM's recent launch of solid state disc storage products for the enterprise was an endorsement of a much misunderstood technology. Could it be time to take this seriously?

When IBM launched a range of solid state disc (SSD) technology, the company had problems generating interest. This despite the fact that it would complement one of the hottest new technologies, virtualisation in the enterprise, with SSD that could fit into its blade servers. "Virtualisation is hot. But we have been cold on SSD," admitted Charlie Andrews, IBM's director of system storage products, "we want to get into more conversations about SSD."

A solid-state drive (SSD) is a data storage device that uses solid-state memory to store persistent data. Unlike the flash-based memory cards used in digital cameras and mobile phones, a SSD emulates a hard disc drive, thus easily replacing it in most applications. An SSD using static random access memory (SRam) or dynamic random access memory (DRam) (instead of flash memory) is often called a Ram-drive.

The two types of SSD, Flash and Ram, can be deployed as enterprise storage media. Ram is more stable and has a better reputation for endurance than Flash. But Flash is quicker. The fundamental flaw in Flash is that it wears out after several writes, However, manufacturers have created memory controllers, which spread the allocation of data to this medium. This has led to a flood of new products coming on the market.

SSD may prove a revelation in enterprise storage. It is, arguably, a better technology - being faster and more resilient than the hard discs that are traditionally deployed.

It is also more compact, so it could possibly help the datacentremanager make a saving on office space. Last, but not least, it uses less power, which will help IT managers stick to a corporate social responsibility agenda, even if they do not recoup all their investment when the electricity bill comes in.

Clive Longbottom, service director of Quocirca, says, "If you have IT systems, which involve high levels of input output, you might have to upgrade the disc technology every two years anyway, as the market moves so quickly,so provided you have the money, you might find that SSD is a good investment. It certainly gives something to those companies than need a competitive advantage."

SSD can simply be acquired as a replacement for normal hard discs. Companies such as Hewlett-Packard, EMC and Hitachi are all producing SSD Flash products for use as storage arrays (akin to Redundant Array of Independent Discs storage arrays).

Another option to consider is to use SSD not as a replacement, but as a complement to existing technology, advisesHamish Macarthur, managing director of storage analyst Macarthur Stroud. One option is for enterprises to attach Flash or Ram to boards, which are then connected via a PC card to the backplane of a server. These boards, which could be provided as memory or fast storage, then offer as a separate entity. Though this idea is not without its challenges (there are data protection issues) it does at least mean that storage, kept separately outside of the server, is easier to protect.

Finally, there is the option offered by Texas Memory and latterly EMC, which is a rack-mounted system of Ram or Flash-based SSD, which can hook up to a server, or network-attached storage (Nas), or be part of a storage area network (San) configuration.

Some large enterprises are already calculating that this technology can lower their total costs of ownership. "We look at the whole life cost of the hardware," says Geoff Connell, the CIO for the London Borough of Newham. "So if it requires less cooling or draws less current then we would be prepared to pay more."

But SSD is not there yet. "We would need many SSDs to give the same capacity as a disc. This negates the power savings," he says.

Clearly the cost of memory is going to make SSD less attractive froma total cost of ownership perspective compared to hard disc drives.

However, as storage analyst Macarthur Stroud predicts, the price will come down rapidly in the next two years. "Virtual environments will demand a new way to meet storage challenges. And the cost of SSD will be more competitive," says Hamish Macarthur, found of Macarthur Stroud. SSD is already an option in some laptop computers. It is only a matter of time before server computing starts to benefit.

What is SSD?

The original usage of the term solid-state (from solid-state physics) refers to the use of semiconductor devices rather than electron tubes, but has in this context been adopted to distinguish solid-state electronics from electromechanical devices as well. With no moving parts, solid-state drives are inherently less fragile than hard discs, so they arealso silent (unless a cooling fan is used) as there are no mechanical delays, they usually enjoy low access time and latency.

Can you justify SSD? >>

Lowering the total cost of ownership >>

Storage performance benchmarks >>


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This was first published in October 2008

 

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