Solid state drives
- 03 December, 2007 07:50
For laptop owners, flash-memory drives boost battery life and performance while making notebooks lighter and more bearable for frequent business travelers. In the data center, benefits include higher reliability than their magnetic counterparts, lower cooling requirements and better performance for applications that require random access such as e-mail servers.
So far, the biggest barriers to adopting solid-state drives (SSD) in the data center have been price and capacity. Hard disk drives (HDD) are much less expensive and hold much more information. For example, a server-based HDD costs just US$1 to US$2 per gigabyte, while SSD costs from US$15 to US$90 per gigabyte, according to IDC.
Capacities are just as disparate. The Samsung SSD drive only holds 64GB, although the company plans to release a new 128GB version next year. Meanwhile, Hitachi America makes a 1TB HDD that's energy efficient and priced at US$399 for mass deployment in servers.
Enterprise Strategy Group analyst Mark D. Peters explains that solid-state technology has been on the radar for years, but has not been a "slam-dunk" in terms of price and performance for corporate managers. That's about to change, he says, because the IOPS (input/output operations per second) benefits to SSDs are too impressive to ignore. Advantages include how SSD has no moving parts, lasts longer, runs faster and is more energy efficient than an HDD.
And prices are falling fast. Right now, the industry trend is a 40% to 50% drop in SSD pricing per year, according to Samsung.
The arrival of hybrid drives such as Samsung's ReadyDrives -- which use both SSD and HDD technology -- and SSD-only servers "suggests the time for SSD as a genuine -- and growing -- viable option is getting closer," says Peters. He was referring to the recent IBM announcement about BladeCenter servers that use a SSD.
"Price erosion, coupled with increased capacity points, will make SSDs an increasingly attractive alternative to HDDs" in data centers, agrees Jeff Janukowicz, an analyst at IDC.
Two examples of how SSDs solve persistent throughput problems for high-performance computing shows how SSD technology may make new inroads in corporations in 2008, some industry watchers believe.
Solid-state at the Stanford Linear Accelerator Center
At this research center, SSD is being used for some of the most data-intensive work going on today. The Stanford Linear Accelerator Center (SLAC) uses particle accelerators to study questions, including where antimatter went in the early universe and what role neurexin and neuroligin proteins play in autism.
The amount of data is immense -- in the petabytes -- and the lab uses a cluster of 5,000 processor cores. Despite that, the discrete chunks of data that are requested and analyzed by several hundred researchers are highly granular -- usually just 100 to 3,000 bytes of information. At the same time, scientists tend to perform thousands of data requests, accessing a few million chunks of data per second.
Richard Mount, SLAC's director of computing, explains that the response time for these researchers' data requests is limited not by the number of processors or by the amount of network bandwidth, but rather by disk access time. "Flash memory is over a thousand times faster than disk" drive technology," says Mount. "Hard disks are limited to around 2,000 sparse or random accesses per second. When accessing thousand-byte chunks, this means that a disk can use only 1/50th of a gigabit-per-second network link and less than 1/100,000th of a typical computer center network switch capacity."
This limitation has translated into the need to make what the lab calls "skim data sets." In other words, preassembled collections of related data that at least one researcher has already requested. "There is no waiting for skim data sets that already exist, but if somebody wants one that does not already exist, then they normally have to wait for a skim production cycle that takes place once every four to six months," Mount says.
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