Multiple processors maximum performance

Playing chess, predicting the weather and simulating nuclear explosions are highly CPU-intensive applications. IBM's latest Deep Blue chess master, for example, is a 32-node IBM RS/6000 SP high-performance computer, and each node has eight onboard CPUs. The 256 processors work together to calculate 60 billion chess moves within three minutes, the time limit for each player's turn.

But Deep Blue might find itself in deep trouble if it had to process claims for a large insurance company or track reservations for a large hotel chain.

For years, capacity planners have reminded CIOs that a computer, network connection or workflow process is no faster than its slowest component. Adding more processors to a server doesn't in itself confer scalability to the applications that the server runs. Replacing a two-way server with an eight-way one won't provide faster performance for an I/O-bound application.

In most business environments, matching CPU power with disk and network I/O throughput is the key to getting work done. In some cases, a multiprocessor computer wedded to a storage-area network (SAN) may be the answer, while clustering is right for others. Use a capacity planner to help choose and configure your servers.

If the application is designed to take advantage of extra CPUs, multiprocessor servers are an effective and appropriate tool for CPU-bound software. All modern server operating systems including OS/390, Windows NT Server, Windows 2000 Advanced Server and Datacenter, Solaris, AIX, HP-UX and Linux can concurrently execute computer programs on different CPUs. Still, the application's design determines how well the software can use multiple CPUs. Moreover, balancing quicker I/O with a symmetrical multiprocessing (SMP) environment can help you see real improvements in transaction response times or get more work done in a given time frame.

Hilton Hotels Corp. has 85,000 employees, more than 400 properties with more than 140,000 rooms, and a sizable franchise operation. With the logistics involved in booking rooms, scheduling banquets and buying tons of fresh food, Hilton rivals a major airline in its need for automation. Damien Bean, vice president of corporate systems at Hilton's Beverly Hills headquarters, says the company's major applications all lend themselves to concurrent operation on SMP servers.

Hilton uses in-house-developed applications to process room reservations and manage each hotel's front-desk chores. One of them runs on RS/6000s. For the front desk, another proprietary application, acquired when Hilton bought another hotel chain, runs on Intel Corp.-based computers. The company also uses PeopleSoft 8 and employs WinFrame software from Citrix Systems Inc. throughout the enterprise. Hilton is now migrating from Microsoft Corp. SQL Server 6.5 to 7.0.

Besides the diverse platforms used by independently owned franchises, Hilton has six HP 9000s running HP-UX, three Sun Microsystems Inc. Enterprise 10000s running Solaris, several RS/6000s running AIX, a pair of AS/400s and more than 400 Windows-based Intel servers. Few RS/6000s have multiple processors, but one HP 9000 has 20 (out of a maximum of 32) CPUs. The HP 9000's applications are I/O-bound, Bean says, so adding more CPUs wouldn't speed processing.

Last November, Hilton began putting SMP-capable servers from Dell Computer Corp. in its properties and Memphis data center. Bean notes that about half of the company's Intel-based servers are SMP-capable most are two-way, but there are a few four- and eight-way servers in the organization. About 20 servers have two network adapters. These SMP server machines run Windows 2000 Advanced Server.

Bean says he avoids I/O bottlenecks in the Dell servers by connecting them via Fibre Channel to Clariion SAN units from EMC Corp. in Hopkinton, Mass. For Hilton, scalability means running the same software in all of the company's different-size hotels. Bean looks at scalability "in terms of negotiating computer capacity with respect to the greatly varying needs of the different hotels and inns," he says, noting that he's happy that the Hilton applications are highly scalable.

"With SMP-capable Intel servers, I can afford to have a spare eight-way database server sitting around as a replacement if there's a problem with the first database server," Bean says. "Furthermore, using EMC's Clariion for data storage means switching to the replacement server is a piece of cake."

Identifying duplicate claims to save money for health insurance companies and health maintenance organizations is a CPU-intensive effort, and the I/O is also nontrivial. Paul Dalberth, a database administrator at Bloodhound Inc. in Research Triangle Park, N.C., says his company's ClaimsGuard Overpayment Protection software plows through reams of health claims on two four-way Dell PowerEdge 6400 servers, using fuzzy logic to flag errors and questionable payments.

Like Hilton, Bloodhound uses EMC Clariion SAN units to store the data for quick access by each SMP server.

Bloodhound has about 20 servers, but the two Dell SMP machines are its workhorses. Each has two Fibre Channel links to the EMC units, as well as two network adapters. Both servers run Oracle8i and SQL Server 7 under Windows NT Server.

The multithreaded claims-review software, written by Hilton programmers in Perth, Australia, lets the software take advantage of the multiple-CPU environment. Dalberth says the multithreaded version processes claims 50 percent to 75 percent faster than a single-threaded version. "Just throwing SMP at a performance problem isn't a good idea," he says. "Making good use of SMP depends on whether the application is designed for it."

If Bloodhound's SMP servers run out of steam as the processing load grows, Dalberth adds, the company will likely use clustering to spread the workload.

SMP Helps You Retire Earlier

Managing investment portfolios and automating a stock exchange trading floor are time-sensitive operations. Chicago-based brokerage firm William Blair & Co. runs a portfolio management application called Advent and a trading-floor front-end application called Moxy on two- and four-way ProLiant DL360 and DL580 servers from Compaq Computer Corp.

Jim Connors, Blair's chief technology officer, says the company has 90 servers, about 20 of which are SMP-capable. The SMP-based e-mail server runs Microsoft Exchange and is the only server with two network adapters. SQL Server 7, the applications' data repository, also runs on a four-way ProLiant server. Windows NT is used for both servers and clients, but Connors' department is upgrading servers and approximately 1,000 desktops to Windows 2000.

Like Hilton and Bloodhound, the brokerage house bypasses the servers' internal hard disks. It stores critical application data in Compaq's StorageWorks SAN environment.

Connors says moving from two-way to four-way servers offered a 50 percent performance gain for the moderately CPU-bound Advent software but only a 10 percent to 20 percent gain for the company's customer relationship management application.

"Using SMP to solve performance problems is sometimes the wrong approach," Connors says. "The problem might be high network utilization, poor application design or just plain too much disk I/O."

"All CPUs wait at the same speed" is a popular dictum among capacity planners. A multiprocessor server is a waste of money if the disk drive or network adapter is the bottleneck. On the other hand, an SMP environment can often turn a CPU-bound sluggard into a thoroughbred racer.

Nance is a software developer and consultant in Wethersfield, Conn.

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