Nov 06 2008

Take a Spin

Solid-state drives offer decent performance at competitive prices. Find out if they are right for your agency.

Computer storage gets no respect. Sure, it’s the workhorse of computing, storing data and serving it up on demand. But for years, there haven’t been many improvements other than increased capacity and better prices.

Today, that’s changing in a big way. The latest news in the world of data storage is the solid-state drive (SSD) — a primary storage device that uses less costly and more efficient dynamic random access memory or flash memory instead of the magnetic media of the traditional hard drive.

Physically, SSDs look very much like traditional hard drives, with similar 1.8-, 2.5- or 3.5-inch form factors and AT Attachment or Serial ATA drive interfaces. The SSD also resides inside a notebook or desktop computer, offering the same basic functions. Right now, capacities can reach 160 gigabytes per drive.

But that’s where the similarities end. Although traditional drives are fairly reliable, with acceptable performance, the latest SSDs offer a performance and reliability boost.

These drives also solve a problem that has plagued the storage industry for years — the need for speed. When a user searches for data on a standard disk drive, the system will locate the data on a specific drive, such as Sector 50, Disk 29. Starting with the sector, it will spin around to find the right disk, and if part of the data is on another disk in another sector, it can take a while to find.

“Seek times are long, and disk drives have miserable rotational latency,” explains Arun Taneja, founder of Taneja Group, a Hopkington, Mass., consultancy.

Faster and More Reliable

Unlike disk drives, which store data on spinning disks, SSDs store data mostly on DRAM at this point, although flash memory is fast gathering steam. Additionally, SSDs use 100 percent random access, meaning they don’t need to read or write in a sequential fashion. That fact alone means that SSDs are much faster than standard hard drives — as much as 200 percent faster in read speed and 60 percent faster in write speed.

“Because there are no mechanical parts or rotating media, it’s faster,” says Jeffrey Janukowicz, an analyst with IDC in Framingham, Mass. “You don’t have to wait for the disk to spin around to find the data, which means end users can access their data much faster.” And because there are fewer moving parts, less can go wrong. For agencies that require as much reliability as possible, that’s a major reason to consider the technology.

Finally, there’s green appeal. “If you have multiple drives in the system, think about the power savings you could amass,” Janukowicz says.

Price Factor

Cost can be a barrier to use. Today, SSDs are more expensive than traditional hard drives. Analysts estimate that an SSD costs about $10 per gigabyte, versus 30 cents per gigabyte for hard drives. Conventional wisdom says the cost must decrease to about $1 per gigabyte before SSDs become affordable for the masses.

fact: 200%: Expected rise in SSD units shipped between now and 2011


Solid-state disk-component pricing has been declining at between 40 percent and 60 percent per year for the past few years, and IDC expects the drop to continue.

But Janukowicz suggests looking at the cost factors differently. Organizations typically compare storage in terms of dollars-per-gigabyte, but it makes more sense to compare it in terms of dollars-per I/O (input/output). “When you compare metrics on an I/O basis, solid-state drives tend to be an attractive solution compared to hard drives,” he says.

Until the prices drop, many organizations are deploying SSDs to satisfy specific needs. A database application that is very sensitive to latency is a good candidate, as are applications that are I/O-limited or I/O-intense. Mission-critical apps such as enterprise resources planning and customer relationship management also are good candidates, Taneja says.

“If system performance is limited, you might consider migrating pieces of a database over to an SSD to increase the overall performance,” Janukowicz says.