TECHNICAL SUPPORT • OCTOBER 2001

BY SAM GOLOB MVS Tools & Tricks

Learning About MVS fromSMF Records and the

IBM Manual

Although it is impossible for us to knoweverything there is to know about

MVS, as practitioners, we strive to keeplearning new things about this operatingsystem. However, how can you go aboutlearning more about MVS? It is importantto find some angles and approaches toMVS knowledge that are useful and pro-ductive to follow. Today, I will show youone unusual approach. Undoubtedly, someof us may have already thought about thisidea, but I know that not everyone has usedthis method of learning MVS in everydaypractice. Therefore, I feel this method isworth discussing. Also, it is somewhatoriginal, but it makes a lot of sense whenyou think about it.

The idea is to learn as much as you canabout MVS by studying the contents of thevarious types of SMF records, and by lookingin the current IBM SMF manual for thetype of material that SMF tries to collect.Since the purpose of SMF is to collect thehistory of your MVS system, it will benefityou to know what type of information thatthe MVS developers believe constitutes“your system’s history.” Therefore, you cangather more “know how” about how yourMVS system actually does work.

I will explain further why this will helpyou learn about MVS. MVS SystemManagement Facilities (SMF) is a way ofrecording for posterity the many transitoryphenomena that tell you how an MVS sys-tem is performing. Most significant actionson an MVS system will cause an SMFrecord to be written to the “active SMFdataset” (a special sequential VSAM file)periodically. Each “type of action” willwrite a different “type of SMF record” to theactive SMF dataset. Additionally, over time,the SMF dataset will accumulate differenttypes of these SMF records.

Now if you want to know what yourMVS system was doing, the informationyou save has to be indicative of all the dif-ferent kinds of actions that the various partsof the MVS operating system constantlyperforms. The MVS developers, whendesigning the format of each type of SMFrecord, studied each part of MVS, trying tofigure out what information was worthsaving. So, what better way to learn theinner-workings of MVS than to look at whichfacts and measurements these developershave decided to save in each appropriatetype of SMF record?

Right now, we will not concentrate on theusual job of how to save the physical SMFrecords for posterity. That is what we oftenthink about when it comes to SMF records.Rather, let’s concern ourselves with tryingto understand the content and format ofeach type of SMF record, so we can grasp

the workings of the MVS component thatcreated it.

I learned a great deal from using thisapproach. Now I will share with you somemore specifics about this idea.

SMF RECORD TYPES

There are 256 valid types of SMF record,and each record is assigned a “type num-ber” from zero through 255. These numberscorrespond to the bit contents of one byte.IBM tries to assign low numbers (less than120 or so) to SMF record types that theyproduce themselves. Other vendors generallyassign high SMF record type numbers or letthe installation choose their own number.Most installations usually choose highnumbers — in the 200s — for user-writtenor vendor-written SMF records.

Additionally, an SMF Record Type maycontain several subtypes. The designationof the subtype also occupies one byte ofthe SMF record. Let me illustrate one casein which subtypes of SMF records areused: For example, job-related and job-step-related accounting information iscontained in SMF Type 30 records.However, information gathered at jobinitiation time gets written to subtype 1.Similar information concerning job steptermination gets written to subtype 4, andinformation concerning job terminationgets written to subtype 5.

A list of the formats of the various “IBM-assigned SMF Record Types” is available inthe current IBM SMF Manual titled MVSSystem Management Facilities (SMF). Themanual number for the z/OS version of theSMF manual is SA22-7630; the OS/390manual number is GC28-1783. I wouldsuggest that you spend some time studyingthis list of formats of SMF records.

The idea is to learnas much as you can

about MVS bystudying the contentsof the various typesof SMF records, and

by looking in thecurrent IBM SMF

manual for the typeof material that SMF

tries to collect.

©2001 Technical Enterprises, Inc. Reproduction of this document without permission is prohibited.

TECHNICAL SUPPORT • OCTOBER 2001WWW.NASPA.COM

GETTING A GRASP OF SMFRECORD TYPES

When you are studying SMF records, Iwould suggest that you read the first coupleof chapters in the SMF manual. That willintroduce you to SMF records in general.After that, I would suggest that you read thechapter on the individual SMF record for-mats titled, “SMF Records.” Once there,carefully read over the “one-liners” thatexplain what each SMF record type isabout. You will discover that there is apattern to the assignment of the SMF recordnumbers. Each component of MVS isassigned a certain range of SMF RecordType numbers, or a certain single numberthat has several subtypes.

For example, SMF record types thatreport on VSAM-related topics are allassigned SMF type numbers from 60through 69. SMF record types that reflectRMF statistics that were collected, allhave numbers from 70 through 79. RACF-related SMF records have type numbersfrom 80 through 83. DB2-related SMFrecords are assigned Types 100 through102. All CICS-related records are in Type110 only. If you are running CICS, youwill probably find a lot of these.Additionally, DFSORT statistics are onlycollected in Type 16 records.

Let me give you a hint on how to lookat the SMF records that are being collectedon your own system: You can use theREVIEW TSO command from File 134 ofthe CBT MVS Utilities collection to pointto any SMF dataset and to browse its con-tents. So why is REVIEW better thanISPF BROWSE? REVIEW has an “SMF”subcommand that formats the timestampsand the type and subtype numbers of allthe SMF records. REVIEW also has a“FINDSMF” or “FS” subcommand, whichwill get you the next SMF record of a cer-tain type. For instance, if you say, “FS14”, REVIEW will position your screen tothe next “Type 14” SMF record and willhighlight it. This facility of REVIEW isextremely handy.

REVIEW can also look at SMF recordson a tape, if you give your TSO sessionthe MOUNT attribute, using the CPSCBcommand from CBT Tape File 300 (or ifyour session has the MOUNT attributealready). When looking at an SMF datasetusing REVIEW, one invocation of the

SMF subcommand will format therecords. A second invocation will toggleback to the raw data. REVIEW is anextremely handy tool for looking at thereal SMF records on your system whileyou are reading about the SMF record for-mats in the SMF book.

Now, let us get back to studying theSMF record formats. After you have goneover all of the SMF types, I would suggestthat you start studying Types 70 through79 in detail. Since RMF collects perfor-mance data from many MVS components,you will gain a ton of knowledge fromstudying the fields of RMF-generatedSMF records.

I will ask another question. If you have anRMF-substitute package, such as CMFfrom BMC Software, and you do not runRMF, CMF will produce its own SMFrecords. Perhaps your installation hasassigned Type 240 for these records. Myquestion is: Do the SMF types 70 through79 disappear when you have CMF? Theanswer is no. You can see this if you reviewthe records in the SMF datasets. You willstill see Types 7x being generated.Afterwards, there will be the Type 240records, too. Why is that? CMF seems to tryto achieve some compatibility with RMF, soif you are converting from RMF to CMF,the reporting stats will not be too different.However, CMF’s own specific extra report-ing will be in the Type 240 records that areproduced at the same time.

Now here is an example of what youcan learn: If you have an SMF bookhandy, turn to the format of Type 71records. There are fields in that recordtype that account for every different typeof SWAP reason code. By looking in thebook, you will see that there are at least17 different reasons why an address spacemight be swapped out. For instance, aTSO address space might be waiting for acommand from a terminal. That is called a“terminal input wait.” You can look in theSMF book to see the names of the 16other SWAP reasons and try to understandwhat they mean. By doing this, you willlearn an awful lot about address spaceswapping in MVS.

I would suggest that you delve into theSMF book on a fairly regular basis to tryto understand the “reasons behind thefields.” You should concentrate on SMFrecord types that concern the parts of

MVS you are dealing with in your regularMVS work.

SUMMARY

SMF records capture the history of whatis going on in your MVS system. Theinformation gathered will reflect the inner-workings of many MVS components.Therefore, if you look in the IBM SMFmanual and vendor manuals that describethe fields of the SMF records being pro-duced, you will learn much more about theinner-workings of that component. TheREVIEW command from File 134 of theCBT MVS Utilities Tape collection canview and format real SMF records on yoursystem and on tape. Using the REVIEWcommand, you can see, on your own sys-tem, the information you are learningabout from the SMF book.

I only have space to give you a hint atthis “different” approach to learning moreabout MVS; the job of “following through”is up to you. If you want to exploit thisenormous opportunity to increase yourMVS knowledge, it lies before you. Take astroll on the path, and enjoy... I hope to seeyou next month!

NaSPA member Sam Golob is a senior systemsprogrammer. He also participates in librarytours and book signings with his wife, authorCourtney Taylor. Sam can be contacted atsbgolob@attglobal.net. The Online CBT TapeWeb site can be accessed from the “MembersOnly” section of the NaSPA Web site atwww.naspa.com.