Data archiving
The prospect of archiving database data can be intimidating at first. One of the misconceptions Marc André, MIS application manager at Chivas Brothers, Paisley, Scotland, encountered when he proposed implementing Princeton Softech's Active Archive software (renamed Optim) was that some users and administrators equated archiving data with deleting data. Some education was required to explain how database archiving products move data from the production database to the archive.

Prior to doing any data archiving, data-retention policies must be established. If it's an internally developed application, more time may be required to understand and document how the application works, and which records can be archived and when. On the other hand, some vendors such as Princeton Softech certify their products with existing apps such as JD Edwards, PeopleSoft and Siebel; HP's RIM for Databases certifies its products with SAP.

App vendors test HP's RIM for Databases software to ensure that it works with their app's public APIs and archives the data in accordance with the way the app expected; how the archiving process worked is then documented. This certification provides users with a level of assurance that archiving will work for these apps, which should get them up and running more quickly.

Tektronix's Hughes initially planned to spend two years developing an archiving solution for the firm's accounts receivable (AR) and customer fulfillment Oracle apps until she discovered HP's RIM for Databases Relocater software. It took two weeks to implement Relocater with the AR app and six weeks to implement it with the customer fulfillment app. "The AR installation was a plain-vanilla installation and went much more quickly than the customer fulfillment, which was slowed by customized policies we had added to the application," notes Hughes.

Users should take precautions and verify that they haven't internally customized the policies of a certified app beyond what it normally delivers. Customization can counteract the certified default policies designed for the app and database archiving software and void the certification. If the app was customized in some way, users will need to adjust the database archiving software's default policies to fit their environment.

The next step is for the database archiving software to copy the indexes, names and schemas of existing production tables, as well as the relationships among them, to the archive. For instance, prior to doing any archiving, Applimation Inc.'s Informia Archive examines the production database to confirm that all relationships between parent and child tables are intact, the transaction is closed, and that the transaction identified for archival meets defined business policies.

HP's RIM for Databases Relocater and Encapsulated Archive each employ HP's RIM for Databases logical unit of work methodology to do archiving. These tools execute the following steps as part of the archiving process:

1. They evaluate data-retention policies and constraints to ensure that a business transaction can be archived/relocated.
2. They copy the business transaction to the archive.
3. They delete the business transaction from the production database.

If storing data in an unalterable format is the primary driver for database archiving, then the data must be stored in a flat-file format such as XML. You can store a database on WORM, but with each new set of archived data the entire database must be archived again, which is neither space nor time efficient.

When creating a secondary instance of the database or providing native application access to the archived data are the principal concerns, the archived data must be stored in a database. Data stored in this format will generally outperform data stored in a flat-file format, but databases can only be stored on standard storage arrays. However, users may choose to put either Fibre Channel or ATA disks in the array depending on the performance required.

Helen Cha, senior director of marketing at OuterBay before its acquisition by HP, cautions that the service-level agreements associated with archived data are very different than those for production databases. She suggests organizations consider how many users will have access to the archive and at what times. She also recommends reconsidering backup plans for database archives because archived data doesn't change; backups only need to be run when new data is added to the archive.

The initial archival run will generally cause the most consternation for users because it's new and likely to be the largest amount of data the archiving app will ever have to deal with. To mitigate these disruptions, database archiving software includes utilities that employ best practices for database management. HP's RIM for Databases Relocater and Encapsulated Archive give users the option to suspend and resume the archiving process. Princeton Softech lets users designate a "cap" that terminates the archiving process after all necessary background processes are completed.

Users may also suspend the archiving process at any time due to performance concerns or an approaching period of heavy production database use. When an archiving operation is suspended, archiving software should roll back the transaction, leaving both the production and archive databases in a consistent state.

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