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ReorgWizard^TM - Reorganize Files Any Time

Why YOU Need This - A Real World Benchmark

An aerospace company has a general ledger detail file with almost 70 million records.  The file had 1.6 million deleted records.  The file has 39 access paths built over the it.  A 'regular' reorg using RGZPFM takes over 28 hours to run.  During that 28 hours, the file is exclusively locked and users can not access the system.

The file was restored and ReorgWizard was used for the file.  The 1.6 million records were shuffled around in only 6.5 hours, during which time the file was not locked and users were not locked out of the system.  To recover the deleted record space does require an exclusive lock, but this step completed in only fifteen seconds.

Exclusive file lock time dropped from 28 HOURS to 15 SECONDS.

The ReorgWizard^TM reorganizes a physical file without locking the file.  The active records are moved to the front, and the deleted records are moved to the back.  No 'smoke and mirrors'.  No journaled, mirrored copies of the physical file and all it's logicals.  The file is reorganized in place and without locking users out of the file..   After the records are reorganized, deleted record space can be recovered quickly.  Finally, you can reorganize files while the users are active!

Files that contain deleted records should be 'reorganized' periodically.  This frees up wasted space, but more importantly it makes database processing more efficient.  Physical I/O's to the database bring 'pages' of data to a program.  A file that has been reorganized will contain more 'active' records in each page, so fewer physical database I/O's will be required.  File scans and searches will be more efficient, since they don't have to waste time looking at (or scanning past) deleted records.

Typically, files are reorganized with IBM's RGZPFM command.  This command gets rid of the deleted records and rebuilds file access paths.  The problem is, the file is locked for the entire process.  Depending on the size of the file, this re-org could take anywhere from a few minutes to many hours to several days!  Further complicating the problem is the fact that once the RGZPFM is started, it can't be stopped without potentially serious consequences.  If a RGZPFM were stopped mid-stream, the file would very likely have to be restored from backup and all the access paths would need to either be restored or rebuilt.  If the access paths were not backed up, you might as well let the RGZPFM finish, because you'll be rebuilding the access paths anyway.  Because of these harsh realities, many shops don't run reorgs or don't run them as often as they should.  They may not have the time (24x7 shops don't have any window, much less one big enough to run reorgs) or they may not want to risk kicking off a reorg on Saturday night if it might not be done for Monday morning.

With ReorgWizard, you won't need to use the RGZPFM command any more.  Reorgs can be run almost any time (as long as some other process doesn't need an exclusive lock on the file).

Even though ReorgWizard doesn't require an exclusive lock, you may have other processes that do - such as the weekly full backup.  Whereas RGZPFM can't be stopped once it's started, ReorgWizard can be run in increments.

ReorgWizard can be run for a subset of the data, or up until a pre-determined date and time.  There is no need to reorg the entire file in one pass.  If your file has 100 million records, you can reorg the first 10 million today, the next 15 million next week, etc.  Or, kick off the ReorgWizard on Friday afternoon and tell it to stop by Sunday at 4pm.  If it's not finished, resubmit it next weekend.  When you resubmit a reorg job, it will pick up where the last one left off.  Chip away at the reorg task as you see fit.  Once the file is completely reorganized, the deleted record space can be recovered with only a brief exclusive file allocation.

Should a process need exclusive file access after the ReorgWizard has started running, the reorg can be ended gracefully from a menu option.  The reorg can then be resubmitted again later to pick up where it left off.

IBM's RGZPFM rebuilds access paths from scratch.  This is one of the reasons that it requires an exclusive lock on the file.  ReorgWizard performs it's access path maintenance while the job is running.  The actual movement of the records is a fairly simple task, but left unchecked the overhead associated with access path maintenance can utilize an excessive amount of system resources and adversely affect other work on the system.

The amazing 'throttle' function in the ReorgWizard allows the reorg job to be slowed down.  This might seem counterintuitive, but it's actually very important.  Any reorg function will involve a tremendous amount of access path maintenance.  This overhead can take over the system - even if the job run priority is changed to try to slow it down.  The throttle feature allows the reorg to be slowed down so that other jobs on the system will not feel the effect of the reorg in progress.  The throttle can be set anywhere from one record per second all the way up to 'full speed'.  So, ReorgWizard can proceed at a pace ranging from a few thousand records per hour all the way up to potentially many millions of records per hour.  The reorg will take longer to process if the throttle is used to slow the job, but since the file isn't locked, that is no longer a critical path issue.  So... you can reorganize the file without locking the users out of the system and without killing performance of the other work on the system!

Finally - the ability to run reorgs.  Finally - reorgs that can be run without RGZPFM and the risk of files being unavailable for Monday morning.  Finally - reorgs that can be run whenever they're needed.  Finally - reorgs that can be run without locking out the users and without adversely affecting other work on the system.

Finally - the ability to utilize the benefits of efficient, reorganized files.

I'm Ready for More ...

1. Want to see an on-line demo of the software?  Need a slide presentation to convince someone else that reorganizing your files is effective, affordable and very do-able?  Click here.
2. What comments have people made about  ReorgWizard?  Click here.
3. Would you like to request a free 30 day trial?  Click here.

Copyright © 1996 - 2008 by DCSoftware, Inc.
Last modified: November 05, 2008  

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