At the risk of appearing more literate than I actually am, I thought a title reference to Elizabeth Barrett Browning's famous Sonnet 43 How Do I Love Thee? was a great way to introduce the topic for this blog. So, how many ways can we run Linux on IBM Power Systems?
- Linux can run as the whole system image (single partition, LPAR) on the system with all resources available to it -- processors, memory and I/O adapters. This is the traditional, non-virtualized configuration typical of x86 servers and sometimes referred to as "bare metal". Since Power Systems has an embedded hypervisor that cannot be removed, the use of the term "bare metal" incorrectly describes a single operating system image running on the complete set of hardware resources in a Power System server.
- Linux (RHEL and SLES) is supported on all Power Systems from the smallest PS70x blades to the largest POWER7 system, the 795, which has up to 256 processor cores. Details about supported servers can be found in the IBM Information Center article titled Supported Linux distributions for POWER7® and POWER6® Servers.
- Linux can run on a partitioned system, along side other operating systems -- IBM i OS, AIX, or Linux -- across the partitions defined on the system. When running multiple Linux versions on the same system in the different partitions (LPARs, VMs), those Linux versions/releases may be either close or diverse in level. For example, one could run a variety of Linux release combinations on the same system, such as a SLES release in one partition and a RHEL release in another, RHEL 6.2 in one partition and 6.3 in another, or SLES 10 SP4 in one partition and SLES 11 SP1 in another. Each partition is separate and unique.
- Linux can run in variety of virtualization configurations of processors, memory, and I/O, from fully dedicated to completely virtualized. Further, Linux supports key PowerVM capabilities such as micro-partitions, dynamic LPAR changes, Live Partition Mobility, and memory over-commit capabilities with Active Memory Sharing. A detailed list of features and the release support specifics can be found in the IBM Information Center article titled Supported features for Linux on Power Systems servers.
- Linux I/O virtualization can be provided through either the Virtual I/O Server (VIOS) or IBM i OS integrated operating environments (NWSD, NWSSTG). These configurations typically manage the disk storage backing the Linux client partitions virtual disk and/or provide some form of network routing or virtualization. Configurations with VIOS also support advanced PowerVM functions such as Live Partition Mobility and Active Memory Sharing.