Solid State Storage Takes a Bite Out of Latency

Although solid-state storage (SSS) has yet to take off, SSS specialist Solid Data Systems ( continues to push ahead. In early July, Solid Data unveiled a series of upgrades to its existing products and a new entry-level SSS device aimed at the e-commerce and service provider spaces.

Solid-state storage defines a method of storing data in a dedicated subsystem composed of physical RAM. Solid-state storage subsystems consist of a battery backup and a fixed-disk subsystem to which the solid-state storage device can dump its data in the event of a prolonged power failure or other system downtime. Solid-state storage is not the same thing as an in-memory database, which caches the contents of a database in the physical memory of an RDBMS. Solid-state storage is deployed on a dedicated subsystem that is both operating system- and RDBMS-independent.

In the area of product upgrades, Solid Data announced that it would effectively double the capacity of its family of file-caching SSS appliances. According to Mike Casey, vice president of marketing at Solid Data, the company is switching from DRAM-based to SDRAM-based SSS storage. This will enable higher capacities at lower prices.

Solid Data’s product line consists of the Excellerator 600, which supports a capacity range from 500 MB to 5 GB; the Excellerator 800 and 800FC, which offer a choice between SCSI and Fibre Channel, boast redundancy features and hot-swappable components and support capacities from 540 MB to 10 GB; finally, the Excellerator 1000 and 1000FC again offer a choice between SCSI- and Fibre Channel-based storage and support storage capacities up to 32 GB.

"I think that in most cases what’s going to be true is that customers know that the prices of the underlying technology come down over time, so they expect to see us pass along cost savings when we adopt new technology," Casey explains. "[These moves will] help to keep it in line with the price of rotating discs."

Product upgrades and price reductions aside, Solid Data’s most important new announcement was its Excellerator 100 SSS device, an Ultra SCSI-based, modular, solid-state file caching appliance -- packed in an rack-mountable 1U formfactor -- that the company says is designed to meet the performance and scalability needs of e-business applications.

In contrast to Solid Data’s bigger and pricier SSS devices -- the Excellerator 800 and 1000 -- the Excellerator 100 doesn’t feature removable fixed disk devices or power supplies. It’s designed to be a modular solution, Solid Data’s Casey says, so if one of the product’s fixed disks or power supplies fails, the unit itself will have to be replaced. In this regard, the Excellerator 100’s 1U formfactor makes it a good choice for deployment in rack-mounted storage farms consisting of tens or even hundreds of SSS appliances.

The Excellerator 100 was designed with quick deployment and setup in mind. It features a plug-and-play installation process that Casey says doesn’t require special tweaking or custom configuring.

"The applications where people will use this typically will be where they have a small application that needs to fit into a small space, and particularly if they don’t expect to scale that up over a period of time," Casey says. "If they’re doing it as part of a data center infrastructure, typically they’ll buy the larger server to scale up, but if they’re using it for e-mail or other similar tasks, they’ll probably go with the 100."

According to Robert Gray, a research manager for storage systems at IDC (, dot-com ventures and other e-commerce outfits are hard-pressed to keep up with continuously escalating storage requirements.

"The dot-coms have had a need to put in storage very quickly and to scale it very quickly," Gray says. "Right now, virtually every storage system supplier views the sweet spot of their market as dot-coms and the Internet."

But in many cases, one or more SSS appliances can eliminate the need for racks of dedicated fixed-disk subsystems. SSS is infinitely faster than disk-bound storage, and -- in I/O-intensive environments -- it can improve overall performance. Applications that are transaction-oriented, for example, generally begin to bog down as fixed disk I/O requests are queued. In some environments, queues can grow to as long as several hours. Because I/O read and write requests happen almost instantaneously in SSS environments, a single SSS appliance supporting an SMTP service, among other examples, can effectively eliminate the need for redundancy and load-balancing across several dedicated servers.

"If it’s transaction oriented, [SSS is] great," Solid Data’s Casey says. "If you’re going after small, random reads, or temporary workspaces for joins and queries, that’s where putting that kind of work on solid-state disk gets your server out of the wait-for-I/O mode.