computer science

SDSF

SDSF is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand SDSF rather than just read about it. In short: The System Display and Search Facility (SDSF) is a component of IBM's mainframe operating system, z/OS, which allows users and administrators to view and control various aspects of the mainframe's operation and system resources using an interactive user interface. Information displayed in SDSF includes batch job output, Unix processes, scheduling environments, and the status of external devices such as printers and…

Key takeaways

SDSF belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect SDSF to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of SDSF from memory before moving on to harder problems.

Reference excerpt

The System Display and Search Facility (SDSF) is a component of IBM's mainframe operating system, z/OS, which allows users and administrators to view and control various aspects of the mainframe's operation and system resources using an interactive user interface. Information displayed in SDSF includes batch job output, Unix processes, scheduling environments, and the status of external devices such as printers and network lines, batch and system log files and dumps.

History Originally written as a field developed program in 1979 by Carl Porter (IBM Sales Engineer), the "SDSF" acronym stood for "SYSLOG Display and Search Facility". The first version of the product allowed the user to browse and search the MVS system log. The next iteration of the product included tabular displays that showed the various JES2 queues on the SPOOL (input, output, held and active jobs) and the acronym was altered to be "SPOOL Display and Search Facility" circa 1987. These displays are collectively known as the "queue panels" and they enable most mainframe users to view and manage their own jobs and output. SDSF became an official IBM program product in the 1980s and later on became an optional component of the operating system as its use was so widespread and important to the administration and operation of MVS. The original design included retrieving information from JES2 and MVS control blocks and was sensitive to any changes to those structures which would require parts to be rebuilt. The product was supplied with source code throughout the 1980s and 1990s. JES2 eventually provided a subsystem interface (SSI) so that SDSF could remove its reliance on control block processing. Over time, a lot of the SDSF code was rewritten from assembler in PLX and this greatly reduced the amount of supplied source code. With z/OS Release 1.9, SDSF supports a REXX interface, allowing batch programs to use SDSF facilities. This support includes stem variables containing SDSF-originated information. Prior to z/OS Release 1.10, SDSF was only supported for use with JES2 and not JES3, although ISV products from Phoenix Software International and Tone Software were available with similar functionality for JES3. At and beyond z/OS Release 1.10, SDSF fully supports JES3, including some new commands (JDS and ODS) to display the data/sets and job output for JES3 jobs. With the release of z/OS V1R13, SDSF came packed with some interesting features like cursor-sensitive sort or point-and-shoot sort and extensive support for open logs from Rexx and Java-programmed environments. As SDSF was enhanced to display more operating system information, its acroynum was changed to mean "SYSTEM Display and Search Facility". In 2015, IBM divested the development and support of SDSF to Rocket Software with a focus on re-invigoration of product functionality. A new server address space "SDSFAUX" was introduced as a SPE for z/OS 2.1 and 2.2 which was a strategic archiectural enhancement for future improvements to the product. The main SDSF server was rewritten in z/OS 2.3 and the display manager code was rewritten in z/OS 2.4. In z/OS 2.5, the legacy internal security mechanisms were deprecated in favour of using SAF resources protected by External Security Managers like RACF, ACF/2 and TopSecret. In z/OS 3.2, SDSF added a python interface (pySDSF) to compliment the existing REXX and Java interfaces.

Features

SDSF is organized as a collection of panels where each panel displays information about a specific aspect of the mainframe's operations. There are over 100 various panels including :

LOG: To see the current log of system activity. DA: "Display Active users/jobs" or running processes. I: Input Queue - shows jobs waiting execution. H: Jobs on HOLD - either waiting to be released into Input or Output or actual copies of job JCL (Job Control Language) or previously executed jobs. ST: Displays current status of all jobs. Job list can be filtered using the PRE primary command. PR: Displays printers. INIT: Displays Initiators (areas where jobs execute or run). O: Output Queue LINE: Network Job Entry (NJE) Lines SR: System Requests MAS: Members in a MAS (Multiple Access Spool) JC: Job Classes PS: z/OS UNIX Processes RES: WLM ( Workload Manager) Resources ENC: Enclaves SE: Scheduling Environments NODE: NJE (Network Job Entry) Nodes SO: Spool offload SP: Spool volumes RM: Resource monitor CK: Health checker APF : APF data sets LNK : Link list data sets PARM : Logical PARMLIB data sets PROC : JES2 PROCLIB data sets SDSF tabular panels provide the user with the ability to issue action characters against the one or more of the rows. Sometimes the action characters will take the user to another SDSF display, sometimes the action character will be translated internally to a MVS or JES command and issued on the user's behalf.

See also z/OS operating system, and its originator MVS

References

External links IBM System Display and Search Facility

Illustrations

Worked examples

Example 1 — a first encounter with SDSF

Start with the simplest possible case. Write down what SDSF claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to SDSF before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about SDSF ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of SDSF

In research: SDSF appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses SDSF in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: SDSF is common in secondary-school and first-year university syllabi. It links to neighbouring topics IBM mainframe operating systems, Mainframe computer stubs, Operating system stubs, so understanding it makes those chapters shorter.
In everyday life: Look for SDSF outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study SDSF in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what SDSF means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain SDSF out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is SDSF in simple terms?

Why does SDSF matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study SDSF?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on SDSF.