Thursday, October 4, 2012

DB2 Utilities Enhancement Tool for z/OS: Easier, More Effective Management of Your DB2 Utility Jobs

John, a colleague of mine, was recently at a DB2 for z/OS site when a problem arose. Someone accidentally ran a LOAD utility with the REPLACE option on a table space that held a considerable amount of data. LOAD did what it is supposed to do when REPLACE is specified in the utility control statement: it cleared all the existing data from the table space and replaced those rows with records from the input data set. Unfortunately, the rows replaced -- and there were a lot of them -- were rows that the company wanted to keep in the table space. As the DB2 DBA team worked to recover the inadvertently discarded data (they were ultimately successful in doing so), John mentioned to the team leader that the problem could have been avoided via the IBM DB2 Utilities Enhancement Tool for z/OS (sometimes called UET). Needless to say, UET is now on that DB2 DBA team leader's "I want this" list.

John was referring in the aforementioned conversation to the syntax monitor function of Utilities Enhancement Tool -- one of several UET features that can enable you to more easily and effectively manage your IBM DB2 utility jobs. The syntax monitor can be used to examine control statements for utility jobs when they are submitted, allowing for prevention of job execution when options on the "no" list are specified (REPLACE, for example, in a LOAD utility statement) as well as addition of desired keywords to utility control statements when those are missing (one organization used UET to ensure that histogram statistics generation was requested for certain RUNSTATS jobs). Now, with respect to the LOAD REPLACE example I've used, you might be thinking that blanket interdiction of REPLACE for LOAD jobs would be overly burdensome in your environment -- perhaps there are times when you WANT to empty existing rows from a table space before adding new rows. Not a problem: Utilities Enhancement Tool allows you to apply a given utility syntax rule very broadly (e.g., at the DB2 subsystem level) or more narrowly (perhaps for a set of user IDs or job names -- you could, for example, set things up so that a utility keyword to be used on an exception basis could only be included in a job submitted by one of your senior DBAs). These rules and their application, by the way, are specified by way of an easy-to-create (and easy-to-modify) UET policy.

In addition to being able to being able to monitor the syntax of DB2 utility control statements, Utilities Enhancement Tool can monitor messages associated with utility job execution. With this capability, you can have UET issue a customized return code when a given message is encountered. That customized return code could be used to automatically trigger a responsive action through your site's automated operations system. Alternatively, operations personnel could be provided with response instructions specifically tied to utility return codes customized through Utilities Enhancement Tool (such an instruction might let operations folks know that a particular situation can be left alone until a DBA deals with it during daytime hours -- DBAs are a lot happier when they are not needlessly awakened in the middle of the night).

UET also delivers some extensions to the standard syntax of IBM DB2 utility control statements. For example, UET allows inclusion of the keyword PRESORT in a LOAD utility statement (an option that would not pass syntax muster in the absence of Utilities Enhancement Tool). When PRESORT is specified for a LOAD job, UET will invoke DFSORT (or, even better, DB2 Sort, if that product is installed on the system) to sort the input file in the target table's clustering key sequence. UET will then change the PRESORT keyword to the DB2 LOAD-recognized PRESORTED option, indicating to the utility that the input records are indeed sorted in clustering key sequence. LOAD will consequently execute its RELOAD and BUILD phases in parallel, and will avoid sorting the table's clustering index. The end result is a LOAD utility job that completes more quickly and consumes less CPU time than would be the case if the input file were not sorted in clustering key sequence.

There's more: when you execute the REORG utility with SHRLEVEL CHANGE to enable concurrent read/write access to the target table space's data, Utilities Enhancement Tool can automatically create the required mapping table for you. UET also provides a capability whereby you can have the tool cancel existing threads and block new threads that could prevent the successful completion of a utility operation.

UET provides you with a lot of useful information through its logging of interactions with DB2 utility jobs. Examining Utilities Enhancement Tool job log data will show you which policy rules were applied and which were not, and why. That knowledge, in turn, can help you to fine-tune your UET policy for a DB2 subsystem.

Of course, Utilities Enhancement Tool supports DB2 10 for z/OS. Like all of IBM's DB2 for z/OS tools, UET was ready for Version 10 when that release of DB2 became generally available a couple of years ago. Consider how UET could help you to introduce new utility keywords (maybe new in DB2 utilities, or just new for your organization) in your DB2 for z/OS environment in a low-risk, systematic, and managed way. Utilities Enhancement Tool can provide for you a new point of control for DB2 utility execution at your site, leading to greater efficiency and productivity, more timely exploitation of new utility control options, and fewer "oops" moments. Give UET a look, and think about how it could deliver for you.

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