Linux on Power

From Wikipedia, the free encyclopedia

Linux is a computer operating system that runs on Power Architecture technology, a microprocessor architecture.

1 Introduction
2 Virtualization on p5 and OpenPower
3 IBM Systems
4 Linux Distributions
- 4.1 Officialy supported distributions:
- 4.2 Working distributions
5 See also
6 External links
7 Articles

[edit] Introduction

Linux on eServer p5 series, formerly called RS/6000 (for RISC System/6000), is a ppc64 Linux port running on IBM POWER based servers. Since the release of eServer p5 series and the Linux 2.6 Kernel, Linux can use POWER5 features such as logical partitioning, micro partitioning and RAS. IBM also has an entry/midrange line of servers called OpenPower which only run Linux - other p5 servers can also run the AIX operating system.

[edit] Virtualization on p5 and OpenPower

Power5 based IBM systems have built in virtualization capabilities derived from mainframe technology. There is an additional layer between hardware and operating systems which is called the hypervisor. IBM p5 systems support up to 256 logical partitions on one machine, with a maximum of 10 per processor. Those micropartitions run in a shared processor pool and can utilize automatic load balancing. The hypervisor also allows the assignment of virtual I/O and network adapters to logical partitions.

For network virtualization it acts as a virtual switch, and a dedicated virtual I/O server (VIO) partition (running a Linux or AIX-based system) provides a bridge to the real network.
Virtual SCSI is achieved through virtual SCSI device assignment to the VIO and client LPAR and linking them to each other, with the VIO server having real storage and parts of it (whole disks, logical volumes or partitions) are shared to the clients.

Any SUSE Enterprise Linux or Debian installation with real resources assigned can be used as a virtual I/O server. There are only two kernel modules: ibmvscsis and ibmveth that needs to be loaded to provide this functionality. Both modules are under the GPL and part of the distribution kernel.

For dynamic LPAR changes (e.g. adding CPU, Memory or removing PCI adapter) on the fly some lopdiags additional packages are needed for RSCT (Reliable Scalable Cluster Technology) communication with the HMC (Hardware Management Console). Those packages are provided from IBM in RPM format but not in source code. After installing this packages dynamic reconfiguration of CPU and hotpluggable PCI adapters can be done without rebooting the operating system. Reducing the memory amount assigned to the logical partition still requires reboot of the target LPAR.