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iTera Boosts Performance of OS/400 File Reorg Tool
by Alex Woodie
iTera recently started shipping a new version of its OS/400 file reorganization tool, Reorganize While Active Version 3.1, that it says runs faster and takes up less disk space than the version it replaces. While iTera officials are not saying how it works for fear of giving its competitors an advantage, the company says users can expect to see a 40 percent performance increase and a one-for-one improvement in the amount of disk space it requires compared to Version 2.
Reorganize While Active allows AS/400 and iSeries shops to keep their applications online while cleaning up production files to eliminate deleted records that are occupying sizable chunks of valuable disk space. The utility is used in place of an OS/400 command, Reorganize Physical File Members (RGZPFM), which requires the OS/400 application to be brought offline while the reorganization is taking place. Both pieces of software allow shops to reclaim disk space, thus improving application response time and delaying, for a time, the inevitable purchase of additional DASD. However, in RGZPFM's case, the amount of application downtime caused by the file reorganization often ranges from a few hours to a few days.
Previous instances of Reorganize While Active used a mirroring process that created duplicate sets of the targeted files on the AS/400 or iSeries server. Changes made to the production file were immediately mirrored in the duplicate file using remote journaling. This process continued until the administrator executed a final file swap, which required the users to log off the application for a minute or so.
This process worked fine for many iTera customers with prudent file sizes. However, because the mirroring process effectively doubles the size of the file, it had the potential to create problems, especially if the user was nearing disc capacity, which is exactly the condition the user was trying to remedy by using the product in the first place. Some of iTera's potential customers have file sizes ranging from 300 GB to 1 TB in size, and the mirroring process was simply not feasible for them.
A Better Solution
So, with Reorganize While Active Version 3.1, iTera introduced an entirely new way to reorganize files and keep the application online without requiring the files to be duplicated. iTera calls this new feature "reorganize in place," and it's available as an adjunct addition--not a replacement--to the mirrored re-org with every shipment of the software.
iTera officials say the reorganize in place method works by grouping deleted records together, removing them, and then compressing the files. But that is all that they'll say about the inner workings of the new method. Details of how the method works and the obstacles that iTera's developers overcame in creating the new method are not being revealed.
The only other tidbit released by iTera officials is that they have added OS/400 commitment controls to the new reorganization method. Commitment control refers to a way in which OS/400 ensures that a unit of work has been properly completed before moving on to the next unit of work. iTera officials say in-house benchmarks show the new reorganize in place method works 40 percent faster than the older mirrored reorganization technique.
Minor Caveats
iTera says there are two types of files that should not be cleaned up using the new reorganize in place method, including files that use referential constraints and files with triggers attached. For these types of files, users should use the mirrored re-org technique. There are controls and safety nets in Reorganize While Active that will prevent users from performing file reorganizations on these types of files using the new reorganize in place method, iTera says.
Additionally, if an AS/400 or iSeries shop is currently using a high availability solution, it may not want to use the new reorganize in place method, officials say. Reorganize in place generates lots of transactions, and adding those to the numerous transactions generated by high availability solutions brings the potential for overwhelming the system.
But Wait, There's More. . .
As if the new reorganize method wasn't enough, iTera has added three other significant features to Reorganize While Active Version 3.1, including a real-time monitor and a new analyzer function.
The new monitor gives the user up-to-the-minute information on the status of file reorgs, including how far along the reorganization process is, how many files are slated for reorganization, and how much longer it will take. It also allows users to view a history of their file reorgs, giving them a better idea of how much time to allot to cleaning the files in the future. The capability to simultaneously reorganize more than one file is also a new feature of this version.
The new analyzer is a piece of software that iTera formerly used during the sales process to show customers how the utility could prove useful. With Version 3.1, the analyzer is included in the utility.It tells the user information such as which files have deleted records, what percentage of a file is comprised of deleted records, and how much disk space would be recovered using the utility.
The new monitor and analyzer should give users a greater insight into how they can use the utility, iTera officials said. Before, it took a fair amount of manual searching--and a bit of luck--to find the files with biggest percentages of deleted records and to figure out which ones would provide the greatest return from a reorganizational investment, and likewise, users had no way of knowing how long a file reorg would take once started.
Reorganize While Active Version 3 was subjected to one-and-a-half months of beta testing before iTera released Version 3.1. The price for the software has not changed: it starts at $3,000 for the P05 processor group. For more information, visit iTera's Web site at www.iterainc.com.
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