In September 2000, IBM introduced the Integrated Facility for Linux (IFL) processor, a specialty engine for and some might say dedicated to running the Linux Operating System. At the time of this announcement, companion software named S/390 Virtual Image Facility for Linux was introduced to assist in the rapid deployment of IFL configurations, especially for non-Mainframe personnel. However, this product was quickly discontinued, in favour of the standard z/VM Operating System, which is not difficult to learn and can accommodate hundreds if not thousands of zLinux images.
Today, the IFL is still a processor dedicated to Linux workloads on IBM System z servers. The IFL is supported by z/VM virtualization and the Linux operating system. The IFL cannot run other IBM operating systems. The competitively priced IFL processor is a CPU capacity enabler, exclusively for Linux workloads. Linux deployment (I.E. SUSE & Red Hat) on IFL’s can reduce expenses in the areas of operational efforts, energy, floor space and especially software.
The IFL provides the following functions and benefits:
- The IBM Enterprise Linux Server is a dedicated System z Linux server, comprised of only IFL processors
- No additional IBM software charges for traditional (E.g. z/OS, CICS, DB2, WebSphere, et al) environment
- Performance improvement for Linux workloads with each successive generation of IFL and System z technology
- Linux workload on the IFL does not result in increased IBM software charges for traditional System z operating systems and middleware
- Same functionality as a General Purpose processor on a System z server
- HiperSockets can be used for communication between Linux images, or Linux and other operating system images on the same System z system
- z/VM virtualization and most IBM Linux middleware products, plus most vendor software products are priced per processor (core) according to the System z IBM International Program License Agreement (IPLA). IPLA products have a one-time-charge (OTC) and an annual (optional) maintenance charge, called Subscription & Support
- Supported by the current z/VM virtualization and IBM Wave for z/VM software versions
- Always a full capacity processor, independent of the capacity of the other processors in the server
- Orderable as a System z hardware feature. The number of orderable IFL features varies by the server model and configuration
- Designed to operate asynchronously with other General Purpose processors
- Managed by PR/SM in logical partition with dedicated or shared processors. The implementation of an IFL requires a Logical Partition (LPAR) definition, where following normal LPAR activation procedure, LPAR defined with an IFL cannot be shared with a general purpose processor.
There will always be the debate as to which processor and associated server type (E.g. x86, POWER, SPARC) is the most cost efficient, but there is no doubt that the ability to accommodate hundreds if not thousands of zLinux instances in one zServer environmental (E.g. Power, Cooling, Floor Space, et al) friendly footprint, with software pricing per core is worthy of consideration.
Adoption for zLinux has been steady and especially in the emerging territories where it’s not unusual for zSeries deployments to be totally zLinux (I.E. IBM Enterprise Linux Server) based. Moreover, the majority of large and traditional IBM Mainframe users (I.E. z/OS) have installed at least one IFL, if only to evaluate the z/VM and zLinux offering. Many have deployed the IFL and associated zLinux solution for business requirements.
Therefore, if one of the major cost benefit features of IFL is optimized software costs; can the IFL processor be considered for other workloads, originating from the traditional zSeries (I.E. z/OS) environments?
Proximal Systems Corporation (PSC) is a company with a solution that transparently offloads data processing from IBM Mainframes to Distributed Systems, with an objective of reducing software cost, while maintaining or improving performance. The company name is derived from the concept of bringing disparate computing systems into close proximity, functionally speaking, providing totally seamless and transparent interoperability. The result is a unified computing complex within which various tasks can be easily migrated between systems to their most cost efficient operating environment, while still being able to interoperate as if they were all hosted together on the same system.
The PSC Proxy Coupling Technology allows for a CPU orientated task to be offloaded from one system to another by means of an associated proxy task, which has an identical interface as the task to be offloaded, but delegates the majority of the processing to an offloaded task on another system. The primary objective of this function are for the cost savings and/or performance improvements that might be delivered by migrating tasks to systems that are able to execute those tasks more efficiently.
The fact that the proxy task maintains the same interface as the application being replaced is crucial; as many past Mainframe migration projects have failed due to insurmountable interoperability problems between the Mainframe and Distributed Systems servers (I.E. Windows, Linux, UNIX, et al). Proxy Coupling Technology offers a solution to this long-standing challenge. In theory, this allows for the transparent offload of a traditional z/OS workload (E.g. Sort) from General Purpose (GP) processors, to a less expensive (E.g. IFL) alternative…
In the first instance, the Proxy Coupling Technology offloads General Purpose CPU workload associated with the z/OS sort (I.E. CA Sort, DFSORT, Syncsort) function, to another platform (E.g. IFL). For IFL based implementations, HyperScokets are utilized to transfer data at memory speeds from the z/OS task to zLinux on the IFL, where the sort operation completes, while the resulting z/OS task and associated data are maintained, as per normal. From an IFL viewpoint, Ahlsort software performs the sort operation, being a sort solution that maintains compatibility with the majority of z/OS sort function (I.E. Control Card Syntax). Therefore, this is a transparent implementation, where the only consideration is how much CPU capacity is required for the offload function (E.g. IFL, x86). The benefits are reduced z/OS MSU usage for the sort function, which can be quite significant, as most business data (E.g. Database Offloads, Customer Orientated, et al) is sorted on a daily if not more frequent basis.
Just as IBM introduced the zAAP on zIIP capability, which allowed some customers to more easily justify a specialty engine (I.E. zIIP), combining workloads to exploit the full capability of the specialty engine; in theory the same ethos applies with the Proxy Coupling Technology. For the avoidance of doubt, workloads that can be processed on an IFL, such as z/OS sort tasks, can assist in delivering higher Return On Investment (ROI) levels for the IFL, for example:
- Reduced z/OS WLC MSU usage (I.E. Sort function offload) and associated software costs savings
- IFL processors run at Full Speed and do not add to traditional workload (I.E. z/OS) software costs
- Utilize any spare IFL CPU resource not used, releasing General Purpose CPU resource for other work
In conclusion, the Proxy Coupling Technology offers a proposition that is similar to the IBM philosophy of reducing z/OS software costs via specialty engines. Seemingly to date, primarily only the zIIP and zAAP specialty engines were available to optimize CPU usage for z/OS workloads. Offloading CPU cycles and thus MSU workload to IFL makes sense, utilizing a cost efficient and indeed a full power CPU engine, where for cost reasons, maybe the majority of z/OS customers don’t deploy the “highest” derivative of General Purpose CPU engine available to them. On the face of it, the realm of possibility exists for other workloads to benefit from z/OS to IFL CPU offload, following sort, which seems to make sense as the first workload to utilize this solution.