Questions remain

Requires Free Membership to View

Performance In the absence of verifiable benchmarks results, it's very difficult to gauge the true performance and scalability of the Symmetrix DMX architecture. Anecdotal reports are promising, but we expect EMC competitors to offer their own retorts to its performance claims.
Cost At press time, EMC declined to discuss the pricing structure of the Symmetrix DMX family. Expect the DMX800 to be priced below the current Symmetrix 8000 line, and the highest-end DMX to command premiums above today's most robust configurations. One thing we do know: DMX disks will cost considerably less than their Symmetrix 8000 counterparts.
Manageability EMC is claiming full software compatibility and a common management interface across the Symmetrix DMX and 8000 families. This should minimize the impact on cost of ownership for the new architecture. But until thousands of DMX units are deployed in live fire environments, it's difficult to say just how smoothly the DMX transition may go.

A change of heart
The Symmetrix DMX represents an important--and overdue--shift in EMC's market approach. Gartner's Passmore singles out EMC's practice of maintaining high list prices and using aggressive negotiating tactics.

"The [Symmetrix] 8000 series was kind of a one-size fits-all product line. Even though they had different models, the salesmen usually jumped in to sell the biggest box," Passmore explains. "They are a much more enlightened company today. They've been listening to the users and listening to the analysts, and the message has been to stop playing games."

Nowhere is the change more evident than EMC's new disk drive pricing structure. Before, Symmetrix disks sold at an exorbitant premium over the off-the-shelf 10,000rpm SCSI disks used in the Clariion. Today, the Symmetrix DMX and Clariion lines use the same standardized disk drives.

"You could pay anything from $11,000 to $18,000 dollars for a [73GB] drive," says Passmore. "If you bought a small handful of drives for the Clariion today, you'd certainly be talking under $1,500."

The fact is, EMC had to do something about its pricing. Cash-strapped businesses have seen IT budgets slashed, and IBM remains a keen price competitor, Passmore says. EMC had already begun aggressively discounting its gear in advance of the DMX release, and that trend should continue. Gibbs says that IRI, for one, has welcomed the change.

"Across my organization, with some very experienced data center folks, they will tell you to a man that the way EMC is going to customers is changing, and significantly for the better."

But other challenges await EMC, Prigmore says. In particular, it must convince IT shops that it is more than a hardware provider, even as it sells a new class of hardware to customers.

"It is easier for the company to train and educate their clients on the new Symmetrix family than to orient them on new software," says Prigmore. "In order for the ship to turn, [EMC] must do both."

DMX Roadmap
For more than a year, EMC has argued that the aging bus architecture in the Symmetrix 8000 line had plenty of headroom to deliver top-line performance. No surprise, the tune has changed at EMC. The question is: Where does Symmetrix DMX go from here?

"Even if technology innovation stopped today, we could improve performance," EMC vice president Chuck Hollis says.

Today each I/O director in the Symmetrix DMX employs eight dedicated matrix links, which Hollis says can be doubled to 16 links without changing the surrounding architecture. Total cache can also be quadrupled, yielding a 512GB global cache that is four times the size of the largest cache currently specified for the DMX2000 line. Finally, the architecture is designed to enable drive counts well beyond the current 288 limit.

"Two-thousand and forty-eight disk drives--that's an exercise in sheet metal. How big do you want it?" asks Hollis. "We think the market will want that class of configuration over the next few years, as they learn that [performance is] disk drive limited."

EMC readily admits that the new architecture leaves plenty of room open for software optimizations. Hollis singles out pipelining that would enable cache cards to read data off one end while writing on the other.

"We're getting very good performance today, but as you learn about an architecture, there is more to do," says Hollis. "We could do a performance roadmap for the next 18 months just on software updates."

Stay the course
One thing EMC couldn't afford was to compromise its strong suite of software and tools. The Symmetrix DMX runs an updated version of EMC's Enginuity operating environment as a common platform for EMC software--including SRDF and TimeFinder--that runs on old or new Symmetrix equipment. The new Enginuity code, says Hollis, focuses on managing changes in the way the matrix architecture transacts data.

"The first thing is all the bus arbitration logic goes away," Hollis explains. "The second thing is that we had to teach [Enginuity] about increased parallelism. We used to have a small number of buses. Now we have eight channels per board. We went from 16 memory regions to 32."

Like any operating system, Enginuity schedules and manages the flow of data through Symmetrix. Enginuity contains the CRC error-correction code, for example, that ensures end-to-end data integrity, and performance optimizing algorithms. EMC also tuned disk mirroring and parity RAID operations, resulting in parity configurations that nearly match the performance of mirrored disks on the Symmetrix 8000, it claims.

Of course, EMC must ensure that the Symmetrix DMX line maintains the highest level of reliability. "[DMX] goes into a customer set that has no tolerance for defects and failures," says Passmore.

Steps EMC has taken to ensure reliability include the use of triple module redundancy with majority voting (TMR-MV) to verify the proper operation of key components in the infrastructure. TMR-MV removes a single point of failure by requiring that at least two of three modules produce identical output. If one module is out of agreement, its input is rejected and the module is flagged as faulty. The three modules link to redundant voters, which route data to cache. If one voter goes down, the second remains online to route the output.

Gibbs says IRI has had no trouble ramping up the new equipment alongside the existing Symmetrix 8730 arrays. What's more, he says the new equipment is proving more flexible and easier to configure than the existing gear, singling out dynamic handling of drive geometries and disk volumes in the DMX product. A switch from a disk mirroring configuration to parity RAID, for example, was seamless.

"The nice thing about the [Symmetrix DMX] is that it is finally approaching the storage-on-demand model, where you can truly add storage and capability as needed," Gibbs says. "In the [old] architecture, once you have the configuration laid out, incremental change in the storage throws it all out of whack."

It's still early for the Symmetrix DMX, and ultimately, its success will be determined by its ability to solve user problems. But the early returns are promising. After a long, long wait, it looks like the Symmetrix is back.

"The matrix architecture is elegantly simple," says Passmore. "The best inventions have simplicity to them and I think this is one of those things."

This was first published in January 2003

There are Comments. Add yours.

TIP: Want to include a code block in your comment? Use <pre> or <code> tags around the desired text. Ex: <code>insert code</code>

REGISTER or login:

Forgot Password?
By submitting you agree to receive email from TechTarget and its partners. If you reside outside of the United States, you consent to having your personal data transferred to and processed in the United States. Privacy
Sort by: OldestNewest

Forgot Password?

No problem! Submit your e-mail address below. We'll send you an email containing your password.

Your password has been sent to: