Fusion-io tries rewiring computer memory

Connecting flash memory to a computer's PCI system offers some speed advantages over hard drives and conventional flash-memory drives. Here's a look at the idea.

Fusion-io's ioDrive Octal, the size of a double-wide video card, can bring as much as 5.12 terabytes of flash memory to a server by through a PCI Express slot.
Fusion-io's ioDrive Octal, the size of a double-wide video card, can bring as much as 5.12 terabytes of flash memory to a server by through a PCI Express slot. Fusion-io

In items like camera memory cards, flash memory is a ho-hum commodity. But when it comes to building flash directly into a computer, the disruption is probably just beginning.

That's why I find Fusion-io an intriguing company.

Fusion-io builds flash memory onto PCI Express cards that plug into server expansion slots, letting customers move beyond hard drives' physical enclosures and SATA interface. That means data can be written and read faster overall, in part because SATA has worse overhead--in other words, bandwidth that must be used to run the communication protocol rather than for the actual data being read or written.

The Salt Lake City start-up isn't the only PCIe storage maker in the market--Texas Memory Solutions' RamSan-10 and the RamSan-20 and OCZ Technology's Z-Drive products are competitors. But Fusion-io has clout: in addition to sales partnerships with IBM, Dell, and Hewlett-Packard, and more than 50 patent applications filed, it's got an investment from flash memory maker Samsung.

Flash crashes the party
For all the change in the computer industry, it's actually pretty rare that a hardware difference comes along that actually is more than an evolutionary tweak to the existing setup.

Flash memory, which has displaced the hard drive in corners of the market such as iPods and high-end laptops and has the potential to do so elsewhere, is one of those changes. It combines the world of conventional computer memory--dynamic random access memory, or DRAM--with the world of hard drives.

DRAM needs a constant supply of electrical power to remember its data, but it can read and write data quickly; hard drives store data even when the power is switched off, and can store much larger amounts of data, but they're relatively slow. Intermediate between the two is flash memory, in terms of data transfer speeds and cost per gigabyte, and like a hard drive it can store data when the computer is switched off.

The first large-scale arrival of flash memory in computers took the form of solid-state drives, or SSDs. They packed flash memory into the type of enclosure that in the past housed a hard drive, and they communicated with the rest of the computer system with the standard hard drive interface, called SATA. Advatages of SSDs include faster data transfer, better ruggedness because of the absence of moving parts, and lower power consumption because the physical platters of hard drives don't need to be rotated all the time.

A nice feature of SSDs is that a computer maker can build a system with them or with conventional hard drives--it's just a matter of deciding which approach is better for the job and connecting the right device.

But for those who are sure flash memory is the right approach, Fusion-io has a different answer: skip the SSD altogether.

Broader than the server market?
Fusion-io aims its products at the server market, but I could see broader application of the idea. Apple's newest MacBook Air laptops , for example, use only flash memory; Apple's engineers used SATA but forsook the hard drive enclosure. As long as you're not building in backward compatibility with conventional hard drives, though, why not take the next step and skip the SATA?

My guess why it's not more common: operating system support, hardware expertise with the idea, and flash memory costs and capacity limits in general. Also, small efficiency gains are more likely to pay in the server market; consumer devices often spend much of their time idling.

The current third-generation version of SATA has a maximum bandwidth of 6 gigabits per second, though that's reduced by the overhead. Fusion-io's lower-end ioDrive matches that rate, it's ioDrive Duo doubles it with 12Gb/sec, and its newest product, the ioDrive Octal, is eight times higher, at about 50Gb/sec. (Note, though, that those are speeds for reading data; writing data is anywhere from the same speed to two-thirds the speed, depending on the model and how much memory it has.)

The ioDrive is modest in scope, with capacities of 160GB, 320GB, and 640GB. The Duo reaches 1.28TB, and the Octal--which is twice as wide--comes in 2.56TB and 5.12TB sizes.

Fusion-io also prides itself on its low latency--the lag between when a data-transfer request is made and fulfilled--and its input-output operations per second (IOPS), an important measure of performance. Last week at the SC10 supercomputing show, it announced the ioDrive Octal reached 1 million IOPS.

Fewer servers
Collectively, this performance essentially places lots of data more conveniently at hand when the processor needs it and gets the reading and writing done faster. That means the server gets its work done, moves on to the next task sooner, and overall is more efficient. That, in turn, lets fewer database servers handle the same amount of work.

Fusion-io's technology isn't cheap. ioDrive is cagey about sharing prices, but the 640GB ioDrive Duo costs more than $15,000 at Dell. That's economical for server customers such as Zappos and MySpace, both of which significantly pared back database servers by adding ioDrive products. And though it's still expensive, the computing industry has proven effective at reducing the price tag of technology like this.

What's not to like? For one thing, Fusion-io is in a way a throwback to days of yore, when storage was build directly into a server. These days, it's common to have standalone storage systems shared by many servers. For another, Fusion-io devices aren't as easily configured for redundancy the way hard drives or SSDs are. And flash memory can essentially wear out through lots of use, though Fusion-io uses "wear-leveling" technology that lets it offer warranties that its ioDrive products will outlast the server they're plugged into.

Clearly, this technology is still in its early days. Even lowly personal computers can suffer hard-drive delays when people launch software or use more software than DRAM memory can accommodate. And there, customers don't have as much need for super-high reliability.

Don't expect the hard drive to fade away any time soon--its cost and capacity advantages are still big. But do pay attention, because the flash memory threat is getting more serious.

 

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