IBM Doubles Down on x86 Server RAM Capacity

The company that introduced the IBM Personal Computer almost thirty years ago is launching a solution it believes will "take the PC out of the PC server" and greatly increase the memory capacity of a standard x86 server. The company's new eX5 Architecture will appear first in blades and racks due out later this year.

"x86 servers today are fundamentally derived from the desktop PC architecture. It's going on 30 years old, and the limitations of that architecture that still manifest today are the main contributing factor to that sprawl and underutilization today," Tom Bradicich, IBM fellow and vice president of systems technology for System x told InternetNews.com.

Memory is make or break for performance. The less reading and writing you have to do to the hard disk, the faster everything becomes. There have been a variety of attempts to address the problem, some successful, such as Cisco's special memory controller on its Unified Computing System blades, and some failures, like the now-defunct MetaRAM.

"The solution to the problem of memory has been throwing more servers at it. If you ran out of memory in your server, the only way to add memory to your workload was to buy another server. To add memory to your app, you had to buy everything," said Bradicich.

As x86 vendors have learned, x86 servers don't scale well beyond four DIMM slots and tend to max out at eight. Memory placed in slots five through eight often runs at a slower clock speed than in slots one through four.

IBM's eX5 Architecture decouples memory from its traditional, tightly bound place alongside the server's CPU, supporting up to 32 DIMMs of extended memory in a single 1u rack or 24 DIMMs on a blade. The rack or blade slides right into a cabinet and the existing server will immediately see the memory and start using it.

The new rack-mounted, memory expansion unit holds 32 DIMM slots. For the two-socket systems, which also hold 32 DIMMs, it's an effective doubling of memory. For the four-socket system with 64 DIMMs, it's a 50 percent increase. IBM's dual-socket blades hold 16 DIMMs and the eX5 memory blade can add another 24.

IBM took this concept from its mainframes and migrated it down to Power-based servers, and now x86. "They have not been explored in the x86 market because of cost and performance issues. This announcement is saying we have overcome those issues. Now with eX5, our customers can only buy what they need and use what they buy. Right now you buy more than you need and don't use it all," said Bradicich.

Long Overdue for x86 Servers

Analyst Joe Clabby, president of Clabby Analytics, said this is long overdue in the x86 market. "If you take a close look at the market, once 64-bit computing arrived, the whole idea was to jam as much data in memory and process it as quickly as possible because so much memory became accessible," he told InternetNews.com.

"So it becomes incumbent on server designers to put as much in memory as possible. A key design point of x86 in multi-core in the future is how much memory can I make available to my CPU and how quick? When you look at what IBM has done with eX5, they are doing what every server vendor should be doing for that exact reason," he concluded.

In addition to the memory controller, the eX5 also adds a new feature called FlexNode, which lets servers add just two CPUs to a server at a time. Before, server upgrades required upgrades of four at a time. Also, FlexNode lets two dual-socket servers "merge" and appear as a single four-socket system and then de-couple back into a pair of servers again as needed.

A Scheduled Provisioning feature lets jobs be scheduled, so interactive applications can run during the day and larger batch jobs run at night on the same system, and there is greater protection from application failover, so workloads are isolated in case they fail.

IBM plans to release ultra-scalable two-socket rack, four-socket rack, and blade versions of the eX5 later this year but could not give specifics, since the release is centered around the release of upcoming Intel (NASDAQ: INTC) Xeon processors.

Andy Patrizio is a senior editor at InternetNews.com, the news service of Internet.com, the network for technology professionals.