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IBM's RS/6000 43P Model 260

March 1999

IBM's RS/6000 43P Model 260

A seriously architectural design for designers of serious architectures.

Ralph Barker

Workstations from Hewlett-Packard (HP), Silicon Graphics Inc. (SGI), and Sun Microsystems tend to get most of the attention within the UNIX community, but IBM's RS/6000 line of workstations also contends for a major share of the market. While earlier versions of the PowerPC chip performed well on integer operations (see our review of the IBM 43P Model 240, October 1997, p. 55), its floating-point performance has been traditionally less than stellar. Additionally, previous versions of IBM's UNIX workstations have been stuck at the 32-bit level, while the competition's top models have long since migrated to 64-bit processors. With the Model 260, IBM has shifted gears to the latest Power3 CPU, currently running at 200MHz. The Power3 CPU is a full 64-bit processor, and supported by the latest 64-bit version of IBM's AIX operating system, version 4.3.2. The big question, of course, is whether IBM can extend this workstation's reach beyond the company's traditional all-blue base.

RS/6000 43P Model 260Of Note

For those expecting another boringly beige desktop chassis like the Model 240, the Model 260 will be a surprise--it's big, beautiful, and black, with a striking industrial design that is reminiscent of Darth Vader without the wheeze. Unlike the smaller Model 240, the 260's deskside tower chassis has ample room for expansion (more on that later), supports large memory configurations, and gets the clutter off the desktop. The Model 260 can be configured with dual processors, up to 4GB RAM, and IBM's new GXT3000P 3-D graphics adapter. Those configuration options let you use the 260 either as an advanced workgroup server or as a high-end graphics workstation.

IBM's new 200MHz 64-bit Power3 CPU features eight execution units fed by the chip's memory subsystem, which is capable of a bandwidth of up to 6.4GB/sec. At first glance, the 200MHz clock rate seems slow when compared with the clock rates of other leading RISC chips. In theory, however, the increased number of instructions per cycle provides the Power3 with significant performance benefits, so the CPU can compete favorably against chips with higher clock rates. Our performance section below examines how well theory stacks up to reality.

IBM's migration to 64-bit computing started with the S70 enterprise server running AIX 4.3. The company's 64-bit strategy is one that permits 32-bit applications to coexist with 64-bit code by making kernel services appear the same to either 32-bit or 64-bit applications. The usual "well-behaved" caveats apply to device drivers and kernel extensions, of course. If you use special device drivers for custom hardware peripherals, you will need to ensure that the device driver conforms to the AIX 4.3 specifications. In general, however, 32-bit AIX applications will run on the 64-bit systems without recompiling them, making the transition easier for you.


We encountered no surprises in the initial setup of the 260's hardware. The system cables conform to conventional industry standards, and ports on the rear of the workstation are well-labeled. Although setup instructions are provided with the system, they are hardly necessary for anyone who has set up a workstation or PC before. Factory installation of the operating system also includes a so-called test-drive software subset.

The test-drive software is an impressive demonstration of the 260's graphics capabilities, and includes several games that show off the system's features. During the initial installation, you are given the option of deleting the test drive, keeping it as part of the system startup, or relegating it to normal execution from the desktop. We recommend either deleting the package or relegating it to desktop execution. If you leave it as part of the system startup, your user will see the same options screen but cannot try those features, because during the initial installation you also set the root password--which is required to perform any of the deletion options. Users are likely to become frustrated when presented with a series of options they cannot perform.

Operationally, AIX 4.3.2 is similar to earlier versions of the OS. The primary user interface is the Common Desktop Environment (CDE), standard on most UNIX workstations. For readers unfamiliar with CDE, it has a graphical environment based on X Window and Motif. At the bottom of the CDE screen is the console, from which you can launch applications and access different desktop environments. Although more-custom desktops can be configured, few users have need for more than the four configured by default. The benefit of these desktops is that each can have its own working environment and start different sets of applications. A developer, for example, might configure different desktops for different development projects, to jump quickly between projects.

From a system-administration perspective, most AIX/administrative functions are performed through SMIT, or its non-graphical equivalent, smitty. SMIT provides a graphical interface to common administrative functions, and executes its underlying commands based on the administrator's selections made through the usual array of buttons and drop-down menu selections. Although SMIT offers powerful options and generally is convenient, you should be aware of the fact that SMIT maintains its own database of configuration options and parameters. Thus, you may not find configuration changes made through SMIT reflected in the traditional system-configuration files.

AIX 4.3.2 includes a good array of utilities to accompany the basic graphical environment. In addition to the usual complement of graphics-oriented utilities common to most CDE implementations, AIX 4.3.2 includes several nifty sound and text-to-speech tools. Although the voice of these utilities is decidedly computerish in tone, it may be endearing to some users.

Printed documentation for the system is scant, but generally conforms to current industry standards in that respect. Installation instructions come with a small manual that describes basic hardware setup and expansion options. Although well-written and easy to understand, the printed manual has little information about rudimentary administrative operations. Like most vendors, IBM assumes that you will install the online documentation and perform any administrative research directly on the system. Online documentation includes online versions of the traditional UNIX manual pages and a searchable set of "books." The factory OS installation, however, does not include all the documentation sets, so you likely will want to install the full set of documentation on your own.

The minimum configuration of the 260 includes one 200MHz Power3 CPU, with 64KB data and 32KB instruction cache, along with 4MB of L2 cache. Base memory is 256MB SDRAM, and the base configuration includes one 4.5GB disk, a 3½-inch diskette drive, and a 32x CD-ROM. Five PCI slots are included on the motherboard, three 32-bit and two 64-bit. Two slots are provided for memory cards, with 16 DIMM slots per card, allowing system RAM to be expanded to 4GB. Peripheral ports integrated into the motherboard include the usual keyboard and mouse ports (PS-2 connectors), an RJ-45 10/100Base-T Ethernet port, two serial ports, one parallel port, stereo audio, an external Ultra SCSI connector, and an integrated digitizer tablet port. Various options are available for installing a tape drive in the one available removable-media bay.

Graphics options for the Model 260 include both 2-D and 3-D boards. The complement of 2-D boards includes the entry-level GXT120P, the Power GXT250P, and the GXT255P. The available 3-D boards are the GXT550P, GXT800P, and the high-end GXT3000P, all "Power" boards. The 3-D boards support OpenGL, GL 3.2, PHIGS, and PEX. The Power GXT3000P board, which came with our test system, supports display resolutions of up to 1,280x1,024 and refresh rates from 60Hz to 85Hz. The GXT3000P also includes 16MB of onboard texture RAM, and four raster engines for improved graphics performance.

One option that garnered considerable attention while the system was in our labs was the IBM 6094 Spaceball Mode 030, essentially a 3-D mouse in the shape of a ball housed on a futuristic-looking curved platform. The spaceball gives you interactive spatial control of 3-D objects, including X, Y, and Z axis controls, along with a series of eight programmable function buttons. Although practical use is tightly coupled to application support, the spaceball is likely to be the most commented-on peripheral on your desktop.


Our review configuration of the 260 included two CPUs and 3GB RAM, along with a second hard disk and a 4mm DDS-3 DAT tape. Thus, we ran both the standard SPEC benchmarks and the multiprocessor version, SPECrate. For those unfamiliar with the SPEC benchmarks, they are a series of CPU-intensive benchmarks that test the floating-point and integer performance. The benchmarks are single-threaded, so neither SPECfp95 nor SPECint95 take advantage of multiple processors.

Inside the RS/6000

The SPECrate versions, however, run multiple copies of the benchmarks simultaneously as a test of the system's multiprocessing capabilities. The SPEC benchmarks are insensitive to the underlying OS, but they are sensitive to compiler optimizations. Thus, the SPEC run rules limit the optimizations vendors can employ. Under the SPEC run rules, vendors can run the benchmarks in single-user mode with a minimum number of system daemons running. But our practice is to run the benchmarks in multiuser mode, with all normal daemons in operation. We believe our practice gives a more accurate picture of the system performance you will see during normal operation.

As you can see in Figures 1 and 2 (SPEC and SPECrate, respectively), the new Power3 CPU in the Model 260 has solved IBM's previous floating-point performance problem. Our runs of SPECfp95 on the 260 resulted in a score of 30.1, which was somewhat higher than the posted scores for other high-end workstations from HP (26.3), SGI (26.6), and Sun (29.5), and over twice the score of Dell's high-end Intel-based workstation (14.7). Integer performance, however, is another story. The Model 260's score of 13.1 on SPECint95, while certainly respectable, is lower than the integer scores of those same competitive machines: 18.9 for Dell's Precision 610 running a 450MHz Intel Pentium II Xeon, 17.4 for the HP 9000 Model J2240 equipped with a 236MHz PA-8200, 13.6 for SGI's Octane powered by a 250MHz Mips R10000, and 16.1 for Sun's Ultra 60 Model 2360 with a 360MHz UltraSPARC II CPU.

Equipped with the Power GXT3000P graphics accelerator, the 260 produces an Xmark93 score of 37.09 and impressive scores on the OpenGL benchmarks: 218.17 for CDRS-03, 16.37 for DX-03, and 7.32 for DRV-04.

How It Rates

The design of the RS/6000 43P Model 260, as mentioned earlier, breaks the mold by being boldly black, and the shape of the chassis has an architectural style that would improve the skylines of most cities. While this dramatic shift in design probably deserved a different model designation, it earns the 43P Model 260 all five Performance Computing flags--outstanding.

Installation of the Model 260 earns an excellent rating. Widely used, industry-standard cables are used for all of the components, and connectors on the rear of the machine are clearly labeled. Although we liked the test-drive software that shows off the capabilities of the system in both an entertaining and informative way, how the software is dealt with could be handled in a better manner. The user, not the administrator, should choose whether to retain or delete the demonstration software, and the script to do so could easily handle the permissions issues. Four flags, nonetheless.

Documentation for the Model 260 is on par with industry standards--not much hard copy, but the online documentation is excellent. While we lament the common fact that many vendors squeeze out a few extra profit dollars by not providing more in the way of printed manuals, we can hardly fault IBM for following the pack. We rate the Model 260's overall documentation as good, three Performance Computing flags.

Expandability of any system is a function of chassis size compared to intended use. IBM's choice of a deskside chassis for the Model 260 gives plenty of room for additional disk drives

How It Rates

and optional media bays consistent with the requirements for either a high-end workstation or a departmental (even small business) server. The 4GB RAM capacity lets you run larger simulations or work with larger engineering models at the desktop if you plan to use the system as a high-end workstation. That memory capacity is also sufficient for demanding server requirements. The Model 260 scores all five Performance Computing flags for expandability.

In operation, we found the Model 260 to be very stable--just what you would expect from a system of this caliber. While we would like to see AIX fully conform to UNIX System V Release 4.x, AIX 4.3.2 does comply with broader industry standards and offers much to be appreciated. IBM, like other UNIX vendors, has maintained 32-bit compatibility with the new 64-bit implementation, letting you run most 32-bit applications on the system without recompiling them. The Model 260 earns an excellent rating for operation, or four Performance Computing flags.

The Model 260's performance surprised us. Earlier PowerPC-based systems were not considered leaders in the performance arena, but IBM has solved its former floating-point performance problem with the new Power3 CPU. The Model 260's integer performance can be considered average, but the system does an outstanding job on both floating-point and graphics performance tests. Considering all categories, we rate the Model 260's performance as excellent.

We think the RS/6000 43P Model 260 takes IBM to a new level in the UNIX workstation market. IBM's workstations have always been popular with the company's traditional customers. With the style and performance of the 260, it is likely to attract a new batch of customers--those who might otherwise favor HP, SGI, or Sun systems. Overall, the Model 260 earns four Performance Computing flags--excellent.

Ralph Barker is senior technical editor for Performance Computing.

IBM's RS/6000 43P Model 260

IBM Corp.
RS/6000 Division
PO Box 100, Somers 3, Route 100
Somers, NY 10589


TESTED CONFIGURATION: Two 200MHz Power3 630 64-bit CPUs, each with 32KBi/64KBd primary cache and 4MB secondary cache; 1GB SDRAM, expandable to 4GB; two 9GB hard disks; two serial ports (db9); one parallel port (db25); built-in audio; 10/100Mbps Ethernet; integrated digitizer tablet port; three 32-bit PCI and two 64-bit PCI slots; two Ultra SCSI controllers, one internal, one external; Power GTX3000P 3-D graphics accelerator with texture mapping; 32x CD-ROM; 1.44MB diskette drive; 20-inch color monitor; 64-bit AIX 4.3.2.

OPTIONS: Prices start at $19,565 for one CPU, 256MB RAM, 4.5GB disk, 32x CD-ROM, keyboard, and mouse (no monitor).
EVALUATION: The Model 260's performance puts IBM head-to-head with the big boys in high-performance UNIX workstations, and helps the system achieve an excellent overall rating.

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