In the x86 world, live migration technologies such as VMware VMotion are table stakes for any virtualization platform worth its salt. Now, some IBM Unix shops have begun to see for themselves what the fuss is about, with the new Live Partition Mobility (LPM) feature in AIX 6 -- a first in the Unix space.
Last year, the University of Pittsburgh Medical Center upgraded about 70% of its Unix systems to AIX 6, said Bill Hirsch, the manager of systems support for AIX. In October, UPMC began using Live Partition Mobility on its IBM logical partitions (LPARs), IBM's venerable virtualization technology.
"It's taken us to a completely new level on Unix virtualization, since it allows us to cross physical boundaries," Hirsch said. He said the firm has performed at least 50 LPM "events" both for testing and production purposes.
The ways UPMC uses LPM closely mimic the use case for live migration on x86: to minimize unplanned downtime, and to balance load.
Before LPM, a firmware upgrade on system might take six or seven hours. "That's just unacceptable," Hirsch said. As a result, firmware updates tended to be put off or performed in the dead of night. By migrating an LPAR to another system using LPM, "we have the freedom to take a downtime."
Similarly, when a workload starts to outgrow its LPAR, Hirsch and his team use LPM. "Since we are so heavily virtualized, we often run into a situation where we are overtaxing a processor. When that happens, we just move it to another server."Lengthening Unix's life span
Conventional wisdom says that RISC-based Unix is a dying breed. Just this week, Bob Muglia, the president of Microsoft's server and tools business, told attendees at the Goldman Sachs technology conference that Sparc was "unambiguously a dying architecture."
And while comments like these are clearly self-serving, the combination of VMware plus cheap, powerful x86 systems has prompted some soul-searching among traditional Unix shops. "[X86] virtualization has triggered [Unix] shops to take a step back from their infrastructure, look at their requirements, and ask, 'Can we virtualize this?' Should we virtualize this?'" said Phil Jaenke, an independent consultant in Cleveland, Ohio, who specializes in Unix systems.
Sometimes, it comes down to money. A VMware virtualization license comes with extensive failover and high-availability capabilities that compete favorably on functionality and cost with Unix high-availability clustering.
"When you look at licensing VMware versus an [Sun] M5000 server with [Symantec] Veritas [Cluster Server and File System], often times VMware is going to come out cheaper," Jaenke said. Provided that x86 can provide the necessary horsepower, that drives many companies to move a lot of their workloads to VMware, he said.
But in some cases, new and improved Unix virtualization features may stem the tide of defection from Unix to x86, said Vic Nyman, the CEO of BlueStripe, an application performance monitoring vendor in Research Triangle Park, N.C. The company recently added support for AIX 6 to its FactFinder 3.1 product in response to customer demand.
"When we first came to market, we were following the VMware wave," Nyman said. "But in the last year, we've seen some of the Unix-flavored virtualization like Solaris Zones and AIX [LPARs] come on like gangbusters."
Generally speaking, "level-two and -three apps are moving over en masse [to VMware], and everyone's happy about that," Nyman said. But when it comes to existing mission-critical Unix applications, "the vast majority [of shops] are more conservative and are adopting evolutionary new Unix virtualization capabilities."
AIX 6 in particular raised the bar, Nyman said. "LPARs have been around for ages, but because they're hardware-based, they're relatively static. Now, they're more virtual and dynamic."