Tuesday, September 30, 2008

A Perfect Storm?

There is something of a perfect storm brewing in the world of data today. The world is becoming more automated, more connected, more wireless, and more complex. The next wave of database administration is intelligent automation. I refer to this as implementing software scrubbing bubbles that “work hard, so you don’t have to.” (Remember that commercial!)

As more of the tasks required of DBAs become more automated, the DBA will be freed to expand into other areas. So one front on this storm is the autonomic computing initiatives that automate DBA tasks. At the same time, IT professionals are being asked to know more about the business instead of just knowing the technology. So DBAs need to understand the business purpose and definition of the data they manage, as well as the technological underpinnings of the DBMS. The driving force here is predominantly regulatory compliance. This second front of the perfect storm will cause DBAs to work more closely with metadata to drive database archiving, data auditing, and security to ensure their organization complies with regulations like Sarbanes-Oxley, HIPAA, and others.

Regarding the wireless aspect of things, pervasive devices (PDA, handhelds, cell phones, etc.) will increasingly interact with database systems. DBAs will need to get involved there to ensure successful data synchronization. And database systems will work with disconnected data seamlessly, such as data generated by RFID tags.

Yet another big database trend is technology "suck." By that I mean the DBMS is as it sucks up technologies and functions that previously required you to purchase separate software. Remember when the DBMS had no ETL or OLAP functionality? Those days are gone. This will continue as the DBMS adds capabilities to tackle more and more IT tasks.

Another trend impacting DBAs will be a change in some of their roles as more and more of the recent DBMS features actually start being used in more production systems.

The net result of this perfect storm of changes is that data professionals are absolutely being required to do more... sometimes with less (less time, less money, less staff, etc.)

If you know the technology but are then required to know the business, this is doing more – much more. But the technology, in many cases, is also expanding. For example, DB2 9 incorporates native XML. Most DBAs are not XML savvy, but increasingly they will have to learn more about XML as the DBMS technology expands. And this is just one example.

Additionally, data is growing at an ever-increasing rate. Every year the amount of data under management increases (some analysts peg the compound annual rate of data growth at 125%) and in many cases the number of DBAs to manage that growing data is not increasing, and indeed, could be decreasing.

And, budgetary limitations can cause DBAs to have to do more work, to more data, with less resources. When a company reduces budget but demands more work, automation is an absolute necessity. Turning work over to the computer can help (although it is unlikely to solve every administrative issue). Sometimes IT professionals fight against the very thing they excel in – that is, automating work. If you think about it, every computer program is written to automate someone’s work – the write (word processing), the accountant (financials, payroll, spreadsheets), and so on. This automation did not put the executives whose work was automated out of a job; instead it made them more efficient. Yet, for some reason, there is a notion in the IT industry that automating IT tasks will eliminate jobs. You cannot automate a DBA out of existence – but you can make that DBA’s job more effective and efficient with DBA tools and autonomic computing.

And the sad truth of the matter is that there is still a LOT more than can, and should, be done in most companies. We can start with better automation of DBA tasks, but we shouldn't stop there!

Corporate governance is hot – that is, technologies to help companies comply with governmental regulations. Software to enable archiving for long-term data retention, auditing to determine who did what to which piece of data, and security to better protect data are all hot data technologies right now. But database security need to be improve and technologies for securing and auditing data need to be more pervasively implemented.

Metadata is increasing in importance. As data professionals really begin to meld together technology and business, they find that metadata is imperative. But most organizations do not have a metadata repository fully-populated and up-to-date that acts as a lexicon for business data.

And finally, something that isn’t nearly hot enough is data quality and integrity. Tools, processes, and database options that can be used to make data more accurate and reliable are not implemented appropriately with any regularity. So the data stored in our corporate databases is suspect. According to Thomas C. Redman, data quality guru, poor data quality costs the typical company at least ten percent (10%) of revenue. That is a significant cost! Data quality is generally bad in most organizations – and more needs to be done to address that problem.

With all of these thoughts in mind, are you prepared to weather this perfect storm?

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Thursday, March 27, 2008

Updated Stored Procedure RedBook for DB2 V9

If you are a stored procedure developer, or a DBA who manages a system with stored procedures - - and you are running DB2 9 for z/OS - - there is an updated RedBook you should download immediately. It is titled DB2 9 for z/OS Stored Procedures: Through the CALL and Beyond. You may have the previous edition, DB2 for z/OS Stored Procedures: Through the CALL and Beyond (SG24-7083)...

This new edition of an all-time favorite RedBook is newly updated to show the changes that have happened to DB2 stored procedures and related tools from V8 to V9. It offers examples and guidelines for developing stored procedures in several languages. You will also find many useful recommendations for setting up and tuning your environment for stored procedures in this free-to-download manual.

And if you are looking for some "stuff" on using Data Studio with stored procedures, this is the place to go... so, it is time to update by downloading this new edition today!

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Friday, January 25, 2008

Get Control of Access Path Changes for Dynamic SQL when Migrating to a New Version of DB2

Are you making plans to migrate to a new version of DB2? Do you know what impact the access changes for dynamic SQL will have on performance? When migrating to a new DB2 version, access path changes for dynamic SQL are unpredictable – as is the impact those changes will have on application performance. Learn how you can use Bind ImpactExpert to eliminate the unwanted surprises in version migration by performing a “precheck” on dynamic SQL access path changes.

This webinar will be presented by myself (Craig Mullins) and Joe Brockert, Sr. Software Consultant for NEON Enterprise Software. We'll discuss the issues associated with dynamic SQL during a DB2 migration and offer a live demo of Bind ImpactExpert. Join us to see the solution that provides predictability in access path changes.

Enroll by clicking on this link.

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Wednesday, January 09, 2008

STOGROUPs and SMS [DB2 9 for z/OS]

With today’s posting we return to our examination of the new features of DB2 9 for z/OS. With V9, DB2 storage groups can be better integrated with SMS storage classes.

Prior to DB2 9, you could only spcify SMS storage classes, data classes, and management classes when using explicit IDCAMS defines. You could use those SMS specifications with your SMS ACS routings, but ACS routines filter on data set names, so those routines could become large and unwieldy if you defined multiple different combinations for different data sets.

The improvement in DB2 9 modifies the CREATE and ALTER STOGROUP statements to utilize SMS classes. This can greatly improve ease-of-use by minimizing the manual effort involved in managing DB2 data sets using DFSMS.

There are three new keywords in the CREATE STOGROUP syntax. You can specify just one, two or even all three of them on one CREATE STOGROUP statement:

  • DATACLAS - influences characteristics such as the data set control block (DCB), striping, extended format usage, extended addressability usage and so on.
  • MGMTCLAS – defines data set frequency of volume backups, migration requirement and related tasks.
  • STORCLAS - define guaranteed spaced and other requirements.


DB2 will not check to verify that the data class, management class, or storage class specified actually exist. In that regard, the parameters are designed to work the same way that the VCAT and VOLUMES parameters have always worked. When the STOGROUP is used to allocate a data set, the specified classes are passed to DFSMS, which does the actual work.

The intent of this posting is not to act as an SMS tutorial. If you wish to investigate the details of SMS in more depth, consult the IBM manual titled -- z/OS DFSMS Implementing System-Managed Storage, SC26-7407.

Additionally, these same parameters have been added to the ALTER STOGROUP statement. When you alter SMS class names of a DB2 STOGROUP, this does not affect the existing data sets. However, if you run the REORG, RECOVER, or LOAD REPLACE utility, DB2 deletes the associated data set and redefines it using the new description of the storage group.

Finally, to accommodate the metadata for these new parameters, three new columns have been added to the SYSIBM.SYSSTOGROUP DB2 catalog table: DATACLAS, MGMTCLAS, and STORCLAS.

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Wednesday, October 10, 2007

RECOVER Improvements [DB2 9 for z/OS]

Our examination of the new utility functionality in DB2 9 for z/OS continues today as we uncover what’s new with the IBM RECOVER utility.

Point-In-Time Consistency

The most significant enhancement centers on recovering to a point-in-time (PIT) with consistency. As any DBA who has ever been charged with recovering an operational database to a prior PIT knows, it can be challenging to accomplish. Of course, if you have a usable QUIESCE point then point in time recovery is easy. But that means you’d have to have planned ahead of time and taken a QUIESCE, which is not always possible with heavy 24x7 workloads.

Well, DB2 V9 offers some relief because the IBM RECOVER utility is enhanced to automatically identify uncommitted work at the PIT to which you are recovering. After detecting the uncommitted work DB2 will rollback any changes made to the database objects that are being recovered. This means that anything that is being recovered will be in a transactionally consistent state. Of course, you still have to make sure that all of the appropriate objects are participating in the recovery.

This works with for PIT recoveries executed with either the TOLOGPOINT or TORBA keywords only. To accomplish this two new phases are added after the LOGAPPLY phase: LOGSCR and LOGUNDO.

The LOGSCR phase runs for each DB2 member with an active unit of recovery (UR). If no UR was active then this phase will be skipped. During the LOGCSR phase, all active and incomplete URs are identified. This includes URs that were:
  • INFLIGHT
  • INABORT
  • INDOUBT
  • POSTPONED ABORT

If any URs were found, the LOGUNDO phase runs. This is where RECOVER backs out
the changes made on recovered objects by active URs. In a data sharing environment, this
will be done one member at a time.

Additional Information on the Progress of Your Recovery

Another improvement made to the IBM RECOVER utility in V9 is the ability to gather more information about the progress of the recovery. Any DBA who has been tasked with sitting around and monitoring recoveries what the DISPLAY command to show accurate, up-to-date, and appropriate information about the status of the recovery.

Well, DB2 V9 enhances the -DISPLAY UTILITY command to provide additional information during the LOGAPPLY phase. DISPLAY now will show the range of the log that needs to be applied, for the database objects that are being recovered. It will also show the progress up to the last commit, as well as the elapsed time since the start of the log apply phase of the recovery.

This information will assist the DBA in determining how long it will take for the recovery job to successfully complete.

Using an Earlier Image Copy

One final enhancement made to the RECOVER utility in V9 gives the DBA control to get DB2 to recover using an earlier image copy. This is accomplished by specifying a point in the log before which DB2 must select an image copy for the recovery.

This technique can be particularly helpful when the most recent image copy is damaged or somehow unusable. You can use an earlier copy by providing an RBA/LRSN value to the new RESTOREBEFORE parameter that is at a point on the log prior to when the unusable image copy was taken.

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Tuesday, October 02, 2007

More Online Utilities [DB2 9 for z/OS]

Today we continue our investigation into the new functionality in DB2 9 for z/OS... and specifically into the improvements made to IBM utilities for version 9. We will turn our attention to improved availability with IBM DB2 utilities. Under DB2 V9, three more utilities can run online – that is, with SHRLEVEL CHANGE.

First up we have CHECK DATA. This utility is executed when you want to make sure that the data in your tables matches your integrity constraints. Prior to V9, access to tables (or table spaces) is read only when CHECK DATA is being run. This means that as long as CHECK DATA is executing you cannot modify data. If you have complex referential sets and/or very large databases you likely will have issues with running CHECK DATA.

You can run CHECK DATA online – that means with SHRLEVEL CHANGE – as of DB2 V9. As with other online utilities, an online CHECK DATA will work with on a shadow copy of the data and indexes. DB2 makes the shadow copy using DFSMS ADRDSSU. This copy can be super fast if you have data set level FlashCopy V2 enabled. Even if you do not have FlashCopy availability will improve because the outage is reduced when you use SHRLEVEL CHANGE (just to make the copy) instead of SHRLEVEL REFERENCE (for the entire utility execution).

DB2 will check data integrity using the shadow copies of the data and indexes. When violations are found DB2 will not set the CHECK pending state. And remember, we are checking shadows, so DB2 will not delete rows in violation. Instead, CHECK DATA will create a PUNCHDDN containing REPAIR LOCATE DELETE input that can be run against the active data.

The CHECK LOB utility has also been enhanced to enable online execution. DB2 V9 allows SHRLEVEL CHANGE for checking LOBs using a shadow copy of the LOB table space. And just like CHECK DATA, DB2 uses the DFSMS ADRDSSU utility to create the shadow. And similarly, the check is executed against the shadow and REPAIR statements are generated that you subsequently can run against the actual LOB table space.

Finally, you can also run the REPAIR LOCATE utility specifying SHRLEVEL CHANGE. This enhancements allows us to execute the REPAIR utility online with LOCATE against indexes, index spaces and table spaces.

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Friday, September 07, 2007

COPY Improvements [DB2 9 for z/OS]

Next up in this sub-series on IBM utility improvements in the larger series on DB2 V9 features and functions we will take a look at the new “stuff” in the IBM COPY utility.

Copying Just the Pending Database Objects

The first nice new feature is a new parameter that can be used to make backup copies of only those database objects in a copy pending state. The new parameter is called SCOPE PENDING, and when you specify it the IBM COPY utility will only copy objects in copy pending or informational copy pending state.

The default is SCOPE ALL, which makes COPY act like it always acted; that is, without regard to the pending state.

This option can be used in conjunction with LISTDEF to build very powerful, selective backup jobs.

Copying Clone Tables

The IBM COPY utility also has been extended to support copying clone tables. If you are not sure what they are, follow the link to the blog entry in this series that covers that topic.

Anyway, the new CLONE parameter must be coded on the COPY specification in order for clone table and index data to be copied. It is important to understand that the CLONE parameter is basically an on/off toggle. If CLONE is coded, then COPY will copy only clone table (and/or index) data. You can specify both clone and regular database objects in the same COPY specification, but the IBM COPY utility will ignore non-clone objects when the CLONE parameter is specified; and it will ignore clone objects if the CLONE parameter is not specified.

CHECKPAGE

The CHECKPAGE parameter is not new to V9, but it is improved. Specifying CHECKPAGE indicates that the COPY utility should check each page in the table space or index for validity. If it finds an error, COPY issues a message that describes the type of error. Using CHECKPAGE is a good idea because it will identify problems in your page sets.

In previous releases of DB2, using CHECKPAGE with COPY was problematic because of high overhead and availability issues. In the DB2 9 for z/OS Technical Overview redbook, IBM reports that the CPU overhead is about 5 percent for COPY INDEX and 14 percent for COPY TABLESPACE if you are running V8. As for the availability issue, as soon as a validity problem is found on a page, the COPY utility will place the page set into COPY PENDING so it cannot be accessed while COPY chugs merrily along looking for additional invalid pages.

Both problems are addressed in DB2 9 for z/OS: IBM has significantly reduced the CPU overhead and fixed the availability issue. Instead of putting the page set into COPY PENDING immediately when it finds a problem, instead COPY will produce the message that it found a problem, but it will not set the pending state. Furthermore, it will continue checking pages but not copying anything.

Upon completion, COPY will issue a return code of 8 and it will update the SYSIBM.SYSCOPY catalog table indicating it found a broken page. This information is recording in a new column, TTYPE, with a value of “B”). This is important to understand because the page set will not be in a COPY PENDING state so you will have to check for the return code and fix the problem.

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Tuesday, September 04, 2007

MODIFY RECOVERY [DB2 9 for z/OS]

Another IBM DB2 utility that has received some attention under Version 9 is MODIFY RECOVERY. For those not sure what this utility is, MODIFY RECOVERY is used to remove records from the SYSIBM.SYSCOPY table in the DB2 Catalog, along with related log records from the SYSIBM.SYSLGRNX directory table and related information from the DBD.

Before the new V9 changed, when you ran MODIFY RECOVERY you had to specify the deletion criteria in one of two ways:

  • Given a specific date, delete all recovery information before that data
  • Or given an age in days, delete all recovery information older than the age

But as of V9 we can alternately specify what is to be retained instead of what is to be deleted. This way, we tell the utility what we want to keep and it will remove the rest.

So, instead of coding the DELETE parameter (with a DATE or AGE) we would instead code a RETAIN parameter. The RETAIN parameter can specify one of five different options:

LAST (integer) – Using this option informs DB2 to choose a date such that the number of full image copies kept is not less than the integer specified. So, if we specify LAST(5), then we will delete all entries that exist prior to the date on which the fifth oldest copy was taken. If more than one copy was taken on that date the result could be that more than 5 copies are retained.

LOGLIMIT – Specifying this option will delete all copies where DB2 no longer has log records to recover forward from. DB2 uses the BSDS to establish the oldest archive log timestamp.

GDGLIMIT – You can use this option to enable the number of copies to be retained to be linked to the corresponding GDG base limit.

GDGLIMIT LAST (integer) – It is possible also to combine the GDGLIMIT and LAST options. DB2 will then use the GDG base limit, if the last primary copy is a GDG, if not it uses the integer specified.

GDGLIMIT LOGLIMIT – And finally, we can combine the GDGLIMIT and LOGLIMIT options, too. If the most recent primary full copy is a GDG then the GDG limit is used. If the last copy is not a GDG then the BSDS is used to determine the date prior to which deletions will occur.

The last two options (the ones that combine two parameters) are particularly useful if you have a mix of GDGs and non-GDGs for your image copies. They are also helpful if you use the LISTDEF option when you make image copy backups.

It is important to understand that for all these options MODIFY RECOVERY will cause DB2 to determine the most recent date that satisfies the retention requirement. After ascertaining the correct date to use, all entries before that data will be deleted. In effect DB2 chooses the most recent date that would satisfy the retention criteria. So, under some circumstances there may be more than one image copy on the specific date that is established, and therefore DB2 will keep those additional copies, too.

As an example, say we take 7 image copies on a single day. Then we run MODIFY RECOVERY … RETAIN LAST (3). In this case, all 7 will be retained as they were made on the same day, even though we indicated that we wanted to retain only the last 3.

Finally, there is one more significant change made to the MODIFY RECOVERY utility. Prior to V9, information was only deleted when copies were removed from SYSIBM.SYSCOPY. But as of V9, MODIFY RECOVERY will deletes SYSIBM.SYSLGRNX entries even if no SYSIBM.SYSCOPY records are deleted.

Why is this important? Well, some shops have migrated over to running BACKUP SYSTEM instead of individual image copies. In this case, there will be no individual image copies to remove in SYSIBM.SYSCOPY, but the SYSIBM.SYSLGRNX records will continue to grow. After migrating to V9 you can use MODIFY RECOVERY to trim the size of SYSIBM.SYSLGRNX which can improve performance for processes that need to access log range information.

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