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Restore issues
If you're responsible for data retention in your organization, you need to address the strategy before the tactical considerations. You'll also need to decide if you should attempt to create a complete plan for recovering data from archives, including media, tape drives, backup applications and data applications, or opt for an alternative approach, such as migrating archived data to SATA-based, second-tier disk storage. Given how rapidly per-gigabyte pricing is dropping, dedicated SATA storage may be less expensive than documenting and managing all of the parts of a tape-based archive solution.

For companies maintaining data on tape, there are several media issues to consider. For example, let's assume there's a formal archiving plan in place; tapes are tested to ensure they're readable and are then rotated offsite and stored in a secure facility. Years later, you receive a request for data that has long since been deleted from your servers; however, you have a catalog of archived data, so you know it's available on a tape that can be requested from the archive company.

When it arrives, you realize you're no longer using drives that support that tape format. You pay twice the original retail price for a drive that will read the tape, but discover it uses a SCSI interface four generations back. You look for a SCSI host bus adapter that will work with the drive, but the only one you can find is an ISA bus card,

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so you end up buying an old PC that has ISA bus slots. However, the latest version of Windows no longer supports the drivers for that card.

You find drivers that work with Windows 2000, and then track down an old copy of Windows 2000 and install it on the server. Luckily, you held onto the old versions of your backup application, so you can finally restore the files. But your sense of accomplishment is short-lived because the files are in a proprietary format created using a program you no longer have ... and the software company is no longer in business. With no other alternatives, you turn to a conversion service that transforms the data into something readable, only to discover that the formatting and fields don't match the other data you're trying to reconcile it with. You spend another few weeks reformatting the data to match.

Organizations like Data Recovery Services of Irving, TX, and ActionFront Data Recovery Labs Inc., a subsidiary of Seagate Technology, can recover data from old tapes or disks, figure out the backup formats and even translate the data into newer file formats. But "you have to look at the overall cost of recovery," notes Scott Selley, senior consultant at ActionFront. "It might be cheaper to re-key the data or use OCR to re-create it from paper."

Forrester Research's Balaouras says companies are increasingly addressing this problem by migrating archives from tape to inexpensive second- or third-tier disk storage. Although this addresses the issues of old tape drives and interfaces, there's still the issue of old data formats at the operating system and application level. Balaouras says data should be renewed on a regular basis to update data formats to those readable by current versions of applications.

Database retention
Existing databases aren't architected for long-term data storage. Though some vendors have proprietary solutions, there are few ways to manage data retention across multiple databases over long periods of time. Databases can hold multiple types of data--transactional, hierarchical and relational--but standard archiving solutions are of little use because all of the files in a database are accessed constantly and data is spread throughout the entire database.

So far, according to Jack Olsen, chief technology officer at Neon Enterprise Software Inc., which provides enterprise data availability software and services, there's "no satisfactory solution" that provides transparent access to data stored in a universal file format; the data shouldn't need to be imported into the same database it started in to restore it. The archive has to be self-sufficient. Considering data may be retained for five to 10 years, the archive has to be independent of the original apps and database structural definitions.

This was first published in October 2006

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