The System p servers, formerly known as the p Series or RS/6000 systems, are based on IBM's Power chip and typically run IBM's AIX version of Unix. A common use of the System p is as a large database server.
System i servers are the former AS/400 mid-range servers, also based on Power chips but running the i5/OS operating system often used by small and mid-sized business.
Both server lines also run Linux; PowerVM may be used with any of the three operating systems.
PowerVM is IBM's established server hypervisor and related software that subdivides physical servers into LPARS or logical partition units, each with its own virtualized operating system and application. PowerVM was formerly known as Advanced Power Virtualization.
PowerVM can now implement a live migration feature, Live Partition Mobility, that moves a single LPARS workload or all LPARS workloads, from one physical server to another without interrupting end users, said Scott Handy, VP of strategy for its Power chip systems, in an interview.
The capability makes it easier to do server maintenance without waiting for server downtime late in the day or on weekends, Handy said. The PowerVM feature is IBM's equivalent to VMware Virtual Center's popular VMotion, which migrates VMware's virtual machines from one physical server to another.
The IBM live migration feature is available only on the Enterprise edition of PowerVM, priced at $1,500 for the System p running Power6 chips, Handy said.
A 16-way System p server with either Standard or Enterprise edition PowerVM can host up to 160 virtual servers, providing a powerful base for server consolidation in the data center, Handy said.
There is also a new, $40 Express edition of PowerVM, designed to encourage entry level use of LPARS virtualization that allows the running of three LPARS per server. The $800 Standard edition allows 10 LPARS per server socket; the Enterprise edition allows the same, Handy said.
Another PowerVM feature is Lx86, which allows a System p server to run most Linux applications built for x86 servers without modification or recompilation. IBM includes the Lx86 feature in PowerVM without additional charge as an incentive to get x86 server users to consolidate servers on the System p. Lx86 is a product of Transitive Corp., a supplier of cross-platform virtualization.
Handy said 70% of System p Power6-equipped servers ship with virtualization as part of the product, a sharp turnaround from IBM's 1999 introduction of virtualization on AIX.
"The Unix customer has been a little slow to adopt virtualization," in part due to the wish to keep database servers or big CRM or ERP applications running without interference. Also, greater utilization gains could be realized by virtualizing x86 servers before Unix servers. Industry analysts claim the typical x86 server utilizes 10% to 15% of the CPU cycles available. Handy said a typical Unix server utilizes 20% to 25%. Mainframes are typically utilized at 60% to 80% of their capacity, he added.
Unix server administrator interest began to change in 2006-2007, as the percentage of servers shipping preloaded with IBM virtualization software rose to 40%. Then the Power6 generation of servers started shipping in June, and virtualization became a dominant feature, shipping with 70% of systems.
It used to be unusual for a database server to also host an application that used the database. "Today you might find the Web tier [Web server and application] right in front of the database on the same server," thanks to virtualization, he said.
Effective management of virtualized systems can lead to 80% energy savings and a 72% reduction in the total cost of ownership, Handy said.