(This is the fourth article in a five-part series.)

Storing multiple instances of identical data in different places is neither green nor smart. The answer: Scour your data for redundant instances and eliminate them, a process known as data de-duplication. EMC Corp. of Hopkinton, Mass., and Cupertino, Calif.-based Symantec Corp. are two of several software vendors offering products that automatically de-duplicate data during backups. According to Taneja Group, an industry analyst firm also in Hopkinton, Mass., de-duplicated backups are up to 25 times smaller than conventional backups, resulting in significant savings on storage equipment and power utilization.

Here are three other ways to make your storage strategy greener:

• Thin provisioning and dynamic capacity management increase your storage efficiency. Both techniques allow you to allocate storage capacity to applications automatically as needed, instead of reserving large amounts of space in advance. That improves disk utilization rates, reducing your need for unused but energy-hungry storage resources.
• Data compression, an old standby, can help you save space on hard drives too. Instead of applying it solely to little-used secondary storage, as is customary, Taneja Group recommends compressing the more frequently accessed data in your primary storage systems as well.
• Storage tiering involves storing frequently used data on disks that receive power continuously, while relegating older, seldom-accessed data to disks that you power up only when needed.

Stan Gibson is a Boston-area technology writer.

Other articles in this series:

Getting started on green IT: Update your hardware

Getting started on green IT: If it’s not in use, turn it off

Getting started on green IT: Virtualize, virtualize, virtualize

Getting started on green IT: Consolidate data centers