What’s an IFL and why should I care?

An overview of “Integrated Facilities for Linux” aka IFLs

I am going to talk about IFLs a lot over the next series of articles so here’s a reference article to explain at a high level what IFLs are.

All computers have processors; most have different types of processors inside the box each optimized to do a specific task. For example, your iPad has a processor for running the actual Angry Birds game and a separate video processor for telling the screen what to display. In theory you can use a single processor for both but you optimize performance greatly if you offload some specific tasks onto a separate independent processor.

In an IBM Series z mainframe there are four main types of processor available: CPs, zIIPs, zAAPs and IFLs. They are all the same physically but they are used for different things and priced differently.

• CPs (Central Processors) will do pretty much anything you want and are the number crunching, MIPS digesting beasts that we expect in a mainframe. They represent the expensive part of owning a mainframe but they do most of the heavy lifting too.
•  zIIPs and zAAPs are just as powerful but are limited to be able to execute only specific tasks: typically DB2 operations and Java/XML processing respectively. These are not included in the MIPS pricing equation and have a significant lower cost of ownership.
• Integrated Facility for Linux (IFLs) are also the same powerful processor hardware as the CPs but they are also limited by microcode to only run…you’ve guessed it – Linux. They are exceptionally inexpensive considering their potential processing potential and do not contribute to the total MIPS in a system’s pricing.

In a nutshell - you can run Linux (specifically Linux for Systemz) on IFLs on your mainframe. Typically you will run these instances of Linux on top of a System z OS called z/VM which allows you to virtualize the Linux instances and run multiple copies on a single IFL.

Note I am not referring to the zEnterprise BladeCenter Extension (zBX) which allows you to run Windows, standard x86 flavors of Linux, etc. No doubt I will later though.