Testing IAM

After you have completed the above steps, including activating IAM you are now ready to test IAM.

Installation verification test

To make a quick test to see if IAM is properly installed in the system submit the job ‘TESTVIF' from the IAM IAMSAMP. This job will execute IDCAMS to DEFINE, REPRO and DELETE an IAM file. A LISTCAT is executed against the IAM file. If IAM is properly installed, LISTCAT will show the file as a non-VSAM file. The IAMPRINT DD statement will display the characteristics of the IAM file. You should also verify from the IAMINFO and IAMPRINT reports that any of the changed Global Options did in fact take effect.

If LISTCAT shows the file as VSAM, then the IAM VSAM Interface may not be properly installed. Review the Installation Instructions to make sure that all required tasks have been completed. If there are any questions, contact IAM Technical Support at BMC.

Important

Before submitting the test job, review the JCL and control statements, making whatever changes are appropriate.

SMF analysis

You are now ready to test IAM in your system. If you are a new user, the first thing you should do is identify your most active VSAM clusters. To aid you in this function, IAM supplies you with a SMF Analysis program (IAMSMFVS). This program is documented in IAMSMFVS — Data Set Analysis Program Overview of this space. To use this program, you must be collecting SMF type 64 and either SMF type 4 or 30 subtype 4 records.

A sample procedure is supplied as member ‘IAMSMFVS' in the IAM IAMSAMP.

Review this procedure making any appropriate changes. You can select from your current SMF data set or from history SMF tapes. It is recommended that you scan from one week to one month's worth of SMF history to get a true picture of your VSAM usage. Submit member ‘IAMSMFVS' to display the VSAM files with the most activity in your system. The first report will display the top 100 VSAM files in descending EXCP order. The second report will display the VSAM files in data set name sequence. Converting just a few of your most active VSAM files can give noticeable and immediate benefits to your CICS and batch systems.

Important

If IAMSMFVS gives a ‘IAM495 NO RECORDS MATCHED SELECTION CRITERIA' message, it probably means that you are not collecting SMF type 64 records. Check SYS1.PARMLIB member SMFPRMxx to see what records SMF is collecting. If type 64 records are not collected, you must change this member. You must issue a SET SMF=xx command to activate the SMF change or wait for your next IPL. After you have collected at least one week’s worth of data, run the IAMSMFVS program again.

General testing

Once you choose which VSAM files you wish to test with, use IDCAMS to DEFINE the IAM files. Take your existing IDCAMS procedure and add the parameter OWNER($IAM) to the DEFINE statement.

Next, use IDCAMS REPRO to copy the VSAM cluster to the IAM file. Run a LISTCAT ALL against the IAM file with an IAMPRINT DD statement specified. The IAMPRINT report will give you the number of tracks used by IAM in addition to all of the IAM characteristics. IAM will automatically release a portion, based on CA% Freespace, of the unused space allocated, if secondary allocation has been specified. Compare this to the VSAM cluster. Unfortunately, it is not easy to tell how much space VSAM really used. If the Data Component HI-USED-RBA is close to HI-ALLOC-RBA, the VSAM file is using most of its allocated space.

If you wish to calculate the space used by the VSAM cluster use the following calculation. Use the values found in the DATA component. Divide the HI-USED-RBA by CISIZE. Divide the result by CIs per CA. Multiply this value by the number of tracks per CA. This will yield the number of tracks used by the Data Component and imbedded index (if specified). Add in the tracks for the Index. This will give you the approximate number of tracks used by the VSAM cluster.

One of the easiest tests you can make is to compare an IDCAMS REPRO of a VSAM cluster and IAM file to tape. Many applications use REPRO to make backup copies of their VSAM files. When the jobs are completed, compare the wall clock time, CPU time (TCB and SRB) and EXCPs issued by each job. This will give you a comparison of the resources used to sequentially read an entire VSAM cluster versus using an IAM file.

Parallel tests

You are now ready to run parallel tests of jobs using VSAM clusters compared to IAM files. Select an application to test, using the IAMSMFVS report as a guide. Use IDCAMS to DEFINE the IAM file specifying a different cluster name then REPRO the VSAM clusters into the IAM files. Use a copy of any files that may be changed by the application. Run the production job against the VSAM clusters. Use the same JCL for the parallel run, changing the JCL to point to the new IAM files. Insert a STEPLIB pointing to the IAM load library if it is not in the LINKLIST. Re-execute the production run using the IAM files. Compare the results from each run. If you do not have the reporting tools necessary to get the SMF data you require, use the IAM supplied program IAMSMF (SMF-basic-reporting-utility). Compare the statistics for each job. You will want to measure the wall clock time, CPU time (SRB and TCB), and EXCP counts (DATA and INDEX for VSAM). In addition, you will want to compare the disk space used by IAM versus the VSAM clusters.

IAMINFO DD statement

Add the following statement to each of the steps using IAM data test.

//IAMINFO DD SYSOUT=*

If this statement is present IAM will print a Run Time Statistics report each time an IAM file is closed. The report will display the characteristics of the file, run time statistics (memory use, read and write I/Os, etc.), count of each command issued (GETS, PUTS, ADDS, DELETES, POINTS), number of buffers used and additional information. There is very little overhead associated with the report because all the statistics are kept regardless of whether or not an IAMINFO DD card is present. The information from the IAMINFO report can be very valuable to you and BMC in determining what each job is doing. (see IAMINFO Reports for details on using this report.)

Testing a new version of IAM

Testing a new version of IAM or a new maintenance level of IAM is straight forward. If you have activated a Concurrent IAM VSAM interface, then just add the appropriate STEPLIB or JOBLIB to the job steps or jobs that you want to run as a test with the new version or level of IAM. If you are using a TEST IAM, then the job names must match the value specified when you last started the TEST IAM along with the appropriate STEPLIB or JOBLIB. By having IAMINFO reports and / or IAMPRINT reports, you can verify that the job is running with the new version or level from the heading on those reports.

CAUTION

If you plan on using the same IAM data sets with V8.1 or older version of IAM, make sure that you do not select Global Options or IAM Overrides that may cause the data set to be unusable under the prior version. Please note that Version 10.01 supports Prime Related Overflow format files and data sets on EAV volumes. Do not create IAM files in these formats if they might be used with IAM 8.1 or older level of IAM.