ReorgWizard Fills a Need for Speed with New 'Reverse' Feature

by Alex Woodie

DCSoftware is shipping a new version of ReorgWizard that includes a new "reverse reorg" feature, which, the company says, can make OS/400 file reorganizations run substantially faster. By starting a file reorg from the last records at the bottom of a file, users of ReorgWizard Version 3.0 should be able to run file reorgs in one-third of the time, and, depending on the condition of the files, possibly up to 90 percent faster, company officials say.

To maximize application response time and to make the most out of available DASD, OS/400 system administrators use a common housekeeping task, called a file reorganization. File reorgs are necessary in order to reclaim disk space taken up by placeholders that remain long after the actual data in a record has been deleted.

IBM offers a file reorg command with OS/400, RGZPFM, but the command is inconvenient for many shops because it requires an exclusive lock on the file. Depending on the file size, users could be barred from accessing that file for a day or more with RGZPFM. Several software vendors, like New England's DCSoftware, have developed their own utilities that allow file reorgs to run "in place," significantly reducing the amount of downtime during file reorgs (although a brief exclusive lock is still required at the end of the procedure). With the new reverse reorg feature in ReorgWizard 3.0, DCSoftware claims it has virtually eliminated the need for downtime with file reorgs.

Unlike the standard sequential reorganization that starts from the beginning of a file, the new reverse reorg feature in ReorgWizard works from the bottom up and moves records from the end to the beginning, which, the company says, has its advantages. For example, consider running a reorg on a file with a million records, 25 percent of which have been deleted. Assuming that deleted files are spread equally throughout the file, a standard sequential reorganization would require moving about 750,000 active records, company officials say. However, because a reverse reorg only fills in the deleted spots, the software would, at most, have to move 250,000 records with reverse reorg, which translates into a two-thirds increase in speed. For comparison, a file with 10 percent deleted records would run in 10 percent of the time of a standard reorg, or 90 percent faster than a sequential reorg. So the fewer deleted records you have in a file, the quicker you can complete the reorg using the reverse feature.

One of DCSoftware's beta sites tested the new reverse reorg feature on a file containing 70 million records, 1.6 million of which had been deleted, the company says. Using IBM's RGZPFM command, it took 28 hours to complete the file reorganization, during which time nobody could access the file. With ReorgWizard's reverse reorg facility, the reorg took 6.5 hours, during which time an exclusive file lock was required for only 15 seconds. The company did not compare the speed of a standard sequential reorg with ReorgWizard's new reverse feature.

DCSoftware has included another time-saving feature with this release of ReorgWizard, the capability to run reorgs in pieces. The new Start, Stop & Resume function in this release allows administrators to resume file reorgs that have been stopped, either because the tool already processed a fixed number of records or because it had come up against a predetermined date and time.

ReorgWizard 3.0 also has enhanced "job throttling" features and additional support for files with check constraints, the company says. The job throttle feature is useful in high-availability environments where journaling is used to synchronize databases. By slowing down the reorg process, it can help the mirrored machine keep up with the primary machine.

ReorgWizard 3.0 supports OS/400 V5R3 and is available now. Licenses range from $499 to $5999, depending on the class of machine. For more information, go to www.arctools.com.