IBM Debuts Beefed-up AIX

AIX 5.2 features dynamic LPAR and capacity upgrade on demand capabilities.

• By Stephen Swoyer
• 10/10/2002

AIX 5L version 5.2 (AIX 5.2) boasts an enhanced implementation of IBM’s LPAR technology that permits system operators to dynamically allocate system resources—including processors, memory and storage—to discrete partitions without rebooting the system.

"[W]e have taken the LPAR capability that was in AIX version 5.1 and extended it one more level such that servers that are partitioned can have resources added to them on the fly while they’re running workloads, without that server or partition having to be brought down to accommodate those resources," explains Mike Harrell, AIX product marketing manager with IBM.

In AIX 5.1, Harrell says, system operators must first allocate or de-allocate resources to an LPAR and then reboot it before changes can take effect. "It was a static implementation [in AIX 5.1]," he concedes.

IBM’s new dynamic LPAR technology comprises a more granular implementation. The newest rev of AIX, for example, can support LPARs of a single processor with 256MB of RAM (AIX 5.1 required a minimum of two processors per LPAR). IBM’s top-of-the-line pSeries 690 server can support a maximum of 32 Power 4 processors, which Harrell describes as a "hardware design point" and not a limitation of AIX.

AIX 5.2’s dynamic LPAR technology is managed entirely in software, to the extent that multiple instances of the AIX operating environment are abstracted from the underlying pSeries hardware that powers them—a topology that Harrell grants "does sound a lot like VM on the mainframe." All things considered, he continues, IBM borrowed extensively from its mainframe expertise when it designed the new AIX. "The technologies that you’re seeing here … for AIX 5.2 are technologies that we have migrated down from the mainframe into our AIX operating system."

According to Gordon Haff, an analyst with consultancy Illuminata, IBM competitors such as Sun Microsystems Inc. and Hewlett-Packard Co. currently provide similar partitioning capabilities in their high-end Unix servers. Because of differences in the way each vendor approaches logical partitioning, Haff stresses, it’s difficult to make a valid comparison between their technologies. Sun’s approach, for example, supports a minimum of two processors per logical partition, but, Haff says, this is as a result of a "hardware building block" design that seeks to maximize overall system availability and recoverability. "It’s a little bit difficult to say A is better than B is better than C, but I can say that [the new version 5.2 release] brings AIX to be roughly on par with what the other Unix vendors are offering."

Another mainframe-like technology that has trickled down to AIX is Capacity Upgrade on Demand, a facility that makes it possible for customers to automatically purchase and deploy additional processing horsepower as their workloads dictate. Many AIX customers purchase pSeries hardware populated with additional Power 4 chips that they "unlock" at a later date to expand their capacity. Capacity Upgrade on Demand can facilitate provisioning of this kind, Harrell explains: "They can quickly add new processors without bringing the system down."

Moreover, Capacity Upgrade on Demand can work in tandem with IBM’s autonomic computing technologies to safeguard the reliability and availability of pSeries hardware, Harrell says. "We call it dynamic processor sparing, [in which] the operating system is constantly checking beneath the covers for the health of the system. If … [the operating system] detects that a processor is getting sick … apacity on demand will reach into a bank of processors that are installed on the system but are not online [and bring up a healthy processor]."

AIX 5.2 boasts new enhancements to the Workload Manager component IBM first shipped in 1999. Administrators can now configure time-based policies for AIX workloads. In addition, Hamrell says, AIX 5.2 features a software enhancement that polls the system for conditions that could cause a CheckStop error and attempts to eliminate them.

Illuminata’s Haff speculates that IBM’s development effort "really shows [its] roots to a certain degree because [its] approach is very much rooted in what [the company has] done in the mainframe in the past." At the same time, he allows, AIX 5.2 still isn’t "as flexible as mainframe partitioning," which supports sub-CPU partitioning. Adds Haff: "You still have minimum of one CPU per logical partition."

In AIX 5.3—due sometime during the first half of 2004, and capable of exploiting enhancements to the Power 5 microprocessor—IBM is expected to deliver sub-CPU partitioning capabilities.

IBM Introduces New Clustering Software

In a related announcement, IBM unveiled version 1.3 of Cluster System Management, a clustering administration tool that can manage both AIX clusters running on pSeries hardware and Linux running on xSeries Intel hardware. "This cluster systems management will manage a mixed set of AIX or xSeries [systems]," Hamrell acknowledges. "It’s able to simultaneously manage Unix loads and Linux loads running together."

In September, IBM forged an agreement with Linux vendor Red Hat to push Linux across its eServer product line. To that end, Harrell continues, IBM will introduce Linux offerings for pSeries by the end of 2002.

"We’re introducing the capability here to manage mixed Linux and AIX environments, but we’re not done. It’s our intention to announce new pSeries product offerings before the end of this year, and even more in the next [year], that are designed to run Linux in a native kind of environment [on pSeries hardware]," he concludes.