Configuring a Virtual I/O Server
Mark R. Bush
Virtualization is a hot topic these days, fueled in part by VMware, Xen, and other impressive technologies. Many commercial Unix vendors now offer server virtualization solutions of some sort. Leading the way by drawing from its mainframe virtualization heritage is IBM with System p5 servers. IBM's virtualization technology is grouped into an orderable feature known as Advanced Power Virtualization (APV). APV enables micro-partitioning (granular to 1/10 of a CPU), Virtual I/O Server (VIOS), Shared Ethernet Adapters (SEA), and partition load manager (PLM). Utilizing the vSCSI and SEA functionality inherent in VIOS, you can create many reliable and robust logical partitions (LPARs) on a single server.
The definition of virtualization is quite varied. One might argue that RAID is a simple form of virtualization -- taking many disks and presenting them to the OS as one LUN (virtually one disk). One definition that I have adopted is taking some physical "real" compute resource and representing it in such a way that allows it to be used by multiple other systems. A simple example using IBM System p5 servers might be dividing up a server with four physical CPUs into eight LPARs, each with its own portion of the CPU's cycles and its own unique and separate version of the complete AIX or Linux environment.
Virtual I/O Server
VIOS software comes with your server if purchased with APV feature. It is an AIX 5.3 mksysb (system image) customized as a specialized appliance that serves up I/O to client LPARs. It has limited functionality and is not to be used for any function other than I/O. The VIOS is loaded into the LPAR of your choice.
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