Most database administrators I've spoken with have never retired the contents of a database. They may migrate the contents of the old database into a newly architected repository, but seldom have they just deleted a database. Or parsed out old data lying around that was clearly obsolete, or possibly truncated tables of sensitive data. DBA's are trained to keep data consistent and make sure the data can be recovered in case of emergency. It's there job, and there is legitimate fear of being fired if you can't produce data when it's requested.
But from a security perspective removing old data is a simple security precaution. Why do I recommend this approach? First off, you can't steal what's not there. If you deleted it from the database and only keep an encrypted tape backup, you're better off if your systems are breached. Second, it's an inexpensive security option that requires no special products and no additional purchases. And as an added bonus, shrinking a database means smaller storage requirements and less overhead on queries, both of which improve performance.
The real problem is this scares the heck out of database administrators. What happens if someone actually wants that data a year from now? Could you recover it? Do you even know who owns it to ask if you can delete it? What if it was subject to regulatory controls you're not aware of? No, it's easier just to keep the data.
And in this day and age where IT keeps more databases, and collects every tidbit of data they can, databases are growing. We collect more data and look for new ways to derive information from it. More data means more information, resulting in better decisions that hopefully provide some competitive sales advantage. Conceptually, anyway. Some firms are under strict regulatory controls to keep data for five- seven-, or even ten years. But studies show data used for analytics purposes goes "bad" -- as much as 30 percent -- after after just 18 months. For your reports that means "Garbage in, Garbage out."
But unlike garbage, bad data does not smell, so DBA's have no good incentive to get rid of it. Until you're breached, that is.
Adrian Lane is an analyst/CTO with Securosis LLC, an independent security consulting practice. Special to Dark Reading.