IFL - Integrated Facility for Linux

Enhanced Definition

An Integrated Facility for Linux (IFL) is a specialized processor engine on IBM Z mainframes designed exclusively to run Linux operating systems and their associated workloads. It enables the consolidation of Linux servers onto the highly reliable and scalable mainframe platform, leveraging its robust infrastructure. IFLs are distinct from general-purpose Central Processors (CPs) and do not contribute to IBM's Millions of Service Units (MSU) metric.

Key Characteristics

- Dedicated Workload: IFLs are restricted to running Linux on Z and z/VM Linux guests; they cannot execute z/OS, z/TPF, z/VSE, or other non-Linux operating systems.
- Cost-Effective Licensing: Software running on IFLs, including z/VM and Linux distributions, often benefits from different, typically lower, licensing costs compared to software running on general-purpose CPs.
- No MSU Consumption: Workloads processed by IFLs do not contribute to the IBM software MSU metric, which is a key factor in the pricing of many IBM z/OS-based software products, leading to potential operational cost savings.
- Integrated Hardware: IFLs are physically integrated into the same IBM Z mainframe hardware, sharing common resources like I/O channels, memory, and networking infrastructure with other engine types (CPs, zIIPs, zAAPs).
- High RAS: They inherit the mainframe's inherent Reliability, Availability, and Serviceability (RAS) features, providing a highly resilient environment for Linux applications.
- Virtualization Optimized: Primarily used in conjunction with z/VM to host a large number of Linux virtual machines, facilitating high consolidation ratios and efficient resource management.

Use Cases

- Enterprise Linux Application Hosting: Running mission-critical Linux applications such as web servers, application servers (e.g., WebSphere Liberty on Linux), and databases (e.g., PostgreSQL, MongoDB, Oracle on Linux) on a highly available platform.
- Server Consolidation: Consolidating numerous distributed x86 Linux servers onto a single IBM Z mainframe using IFLs, reducing data center footprint, power consumption, and cooling costs.
- Development and Test Environments: Providing robust, isolated, and scalable Linux environments for developing and testing applications that may interact with z/OS systems or other mainframe resources.
- Hybrid Cloud Integration: Serving as a secure and high-performance platform for Linux-based components of hybrid cloud solutions, often facilitating seamless integration with z/OS data and applications.
- Data Analytics and AI: Hosting Linux-based data analytics, machine learning, and artificial intelligence workloads, leveraging the mainframe's high-speed I/O and proximity to enterprise data.

Related Concepts

IFLs are a specialized processor type within the IBM Z mainframe architecture, extending its capabilities to efficiently host Linux on Z workloads. They are typically managed by z/VM, which acts as a hypervisor to create and manage multiple Linux virtual machines. Unlike general-purpose CPs which run z/OS and contribute to MSU calculations, IFLs are designed to avoid MSU charges for Linux workloads. They are conceptually similar to zIIPs and zAAPs in being specialized engines, but IFLs are dedicated to Linux, whereas zIIPs/zAAPs offload specific z/OS-related work (e.g., Java, XML, DB2 processing) from CPs.

Best Practices:

Strategic Sizing: Accurately size the number and capacity of IFLs based on anticipated Linux workload demands to ensure optimal performance, resource utilization, and cost -effectiveness.
Leverage z/VM Features: Fully utilize z/VM's advanced virtualization, resource management (e.g., CPU pooling, memory sharing), and high availability features to maximize the benefits of IFLs.
Proactive Monitoring: Implement comprehensive monitoring of IFL utilization, Linux guest performance, and I/O activity to identify potential bottlenecks and ensure efficient operation.
Security Integration: Integrate Linux on Z security with the broader mainframe security framework, leveraging features like System Authorization Facility (SAF) for centralized authentication and authorization where appropriate.
Optimized Network Design: Design a robust and high-performance network infrastructure for Linux guests running on IFLs, utilizing mainframe networking capabilities such as OSA