Implementing Micro-Partitioning on the IBM p5 595 Server
Chris Gibson
When management asked why our IBM pSeries hardware, in particular CPU, was so expensive and whether there was anything we could do to reduce the cost to the business, we reviewed the CPU usage on the majority of our LPARs and realized (like most Unix shops) that our systems were only about 20% utilized most of the time. Some of these systems had many dedicated processors doing very little work a great deal of the time. This idle time was very expensive when you consider each processor could cost in the range of $40K-$100K.
Rather than "wasting" CPU resources, we needed to find a way of increasing our CPU utilization and reducing our hardware costs. The answer was immediately available to us in the form of IBM's new micro-partitioning technology on the POWER5 (p5) platform. This technology, along with Virtual I/O, is part of the Advanced POWER Virtualization (APV) feature (standard with p595) on System p. Micro-partitioning allows a system to virtualize its processors for sharing by multiple LPARs. Virtual I/O (VIO) provides the capability for an I/O adapter to be shared by multiple LPARs on the same managed system. We chose not to deploy VIO to any business system as we were still concerned with its performance; thus, all LPARs would continue to use dedicated adapters.
In this article, I will describe how we moved to micro-partitioning and how we monitored and measured our shared processor pool. Topics covered will include: a brief introduction to micro-partitioning, sizing guidelines, p5 LPAR configuration pointers, monitoring/measuring the shared processor pool, and performance considerations.
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