SSDs Gaining Ground In Storage, Servers, Laptops
Joseph F. Kovar
With the quickly falling prices of Flash memory and the quickly rising number of vendors bringing solid state drives and Flash memory modules to market, the final barriers to the widespread adoption of these technologies have been breached.
Solid state drives and Flash memory modules are alternative technologies to the traditional spinning hard drive for storing data and, in some cases, to the more expensive memory chips which in servers and storage often act as cache memory.
Solid state drives and Flash memory modules offer multiple-times the performance of traditional spinning hard drives. And, because they have no moving parts, they use considerably less power than the traditional drives. However, because they are built using Flash memory chips instead of spinning platters, they are much more expensive than hard drives.
Whether such products start to put a noticeable dent in the market for traditional hard drives in the foreseeable feature is an open question. What's not in question is the expected growth for these devices. IDC, for instance, expects the SSD market to grow at a compound annual growth rate (CAGR) of 54 percent between 2008 and 2013.
Where the technologies are used varies. Customers may put SSDs in arrays in place of spinning disks to serve as primary storage, where their much higher performance compared to hard drives more than makes up for the price premium paid for the technology.
EMC in early 2008 was the first major storage vendor to add an SSD option to enterprise-class storage arrays, an option that has since become available from all its peers and competitors.
In some cases, SSDs can actually lower the cost of storage. For many high-performance applications, customers may often "short-stroke" their hard drives, or configure their hard drives so that only a small portion of the capacity is used to cut down on the seek time for data and increase throughput. This results in higher performance, but at the cost of much lost capacity. The use of SSDs in many cases may result in lower costs because of the increased utilization of storage capacity.
Customers are also putting SSDs or Flash storage modules in front of arrays to serve as a storage cache. In this case, the SSDs or modules are not actually acting as a primary storage device, but instead temporarily hold data which receives a lot of read requests, or hits, to speed up application performance.
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PCIe cards from vendors such as LSI are also starting to become available for configuring inside servers to offer high-speed local storage and application performance, and a consortium of major storage and server vendors are developing a standard specification for PCIe-based SSDs.
SSDs are also increasingly available for use in laptop PCs not only because of their performance, but also because they use considerably less power and can boot a system up more quickly than spinning hard drives. Apple's new Macbook Air, introduced in the fall of 2010, can only be purchased with an SSD, and not with a hard drive. Toshiba, the manufacturer of the Macbook Air SSD, is also making that drive available to other portable PC OEMs.
But not all SSDs are created equal.
There are two types of SSDs, depending on the technology of the Flash memory on which it is built. Some SSDs feature single-level cell (SLC) memory technology, in which one bit of data occupies one cell of the flash memory, making it optimized for performance and data reliability. SSDs offered as "enterprise-class" use SLC technology. Other SSDs feature multilevel cell (MLC) technology, in which four bits of data occupy one cell of the Flash memory for greater capacity.
There are also multiple vendors coming to market attempting to make MLC technology useful in enterprise-class applications by adding algorithms to their controllers to control the read, write, and refresh cycles of the SSDs to increase reliability while keeping the cost closer to that of MLC drives.
Solution providers have been using SSDs for years, sometimes even 20 or more years when the technology was used to boost mainframe performance.
However, they said, despite falling prices and increasing performance and reliability, the market is still a bit slow.
Joe Kadlec, vice president and senior partner at Consiliant Technologies, an Irvine, Calif.-based solution provider, said his company offers SSDs with the arrays it sells from Hitachi Data Systems.
There is still a lot of salesmanship that goes into helping customers decide to add SSDs to their arrays, Kadlec said.
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"We'll recommend it for certain applications," he said. "We'll sit down with the customer, look at its business applications, and point out where the apps might benefit from low latency. And our engineers sit down with a stakeholder at the customer site and do a little digging, maybe use a professional services engagement, to do a deep dive and see where the benefits are."
One thing Consiliant does not do is work with the crop of newer vendors coming to market with SSDs.
"I've found that the data going on SSDs is the most business-critical data," Kadlec said. "Reliability is paramount. I don't want to jeopardize customer data to save a few thousand dollars. Hitachi puts its SSDs through their paces."
Tim Neary, owner and president of Strategic Storage Solutions, an Allen, Texas-based solution provider, has relationships with Texas Memory Systems, one of the pioneers in the SSD market, as well as with Compellent, which in 2010 added SSDs as an option to its Storage Center SAN arrays.
Prices are getting more "palatable" for customers, Neary said. "However, SSD sales takes a lot of expertise. What vendors are doing today, making SSDs a small part of the array and using as a cache, makes sense."
Nearly said that he has yet to sell any SSDs for arrays from Compellent, which in late 2010 is in the process of being acquired by Dell.
"They are still too expensive," he said. "But as customers get mature with Compellent technology, they will see the opportunities. As long as Dell doesn't screw Compellent up."
Mainstream customer use of SSDs is still hit and miss, said Keith Norbie, vice president of sales at Nexus Information Systems, a Minnetonka, Minn.-based solution provider which has sold a few SSDs from EMC.
Norbie said he is also closely watching newer vendors such as Fusion-IO, which offers Flash modules for servers which are lower in cost than SSDs but perform much faster for local applications; startup Whiptail Technologies, a Summit, N.J.-based developer of arrays featuring only SSDs; and companies producing hybrid hard drive and SSD combination devices.