Opinion: Are you being duped by de-duplication technology?

Keeping your backups recoverable and easy to manage is as important as reducing capacity needs

Are users being duped by de-duplication software? Without a doubt, de-duplication software is one of the more intriguing technologies emerging in the storage space. Available in some backup software packages and included on some virtual tape libraries, de-duplication can reduce data stores by factors of 20 or more. While less storage always sounds good to business folks, there are some factors users need to consider before selecting this option.

First, de-duplication software is like encryption software: You lose the key, you lose the data. De-duplication software delivers these significant reductions in data storage by storing the same blocks of data only once. However, if the index that allows you to reconstruct these blocks of data becomes corrupted or destroyed, the underlying blocks of data may also become unrecoverable.

Second, make sure the underlying disk drives on which the data blocks are stored provide adequate levels of protection. Each block of data is potentially used to reconstruct tens, hundreds or even thousands of files and losing even one data block could affect multiple files. Users should minimally configure local disk drives in either RAID 1 or RAID 5 levels of protection, and ideally they should keep a copy of all this data in a separate physical location.

Finally, establish what you hope to achieve by de-duping your data. Minimizing the amount of data you want to store and reducing costs are valid reasons for implementing de-duplication. However, de-duplication software will also likely extend backup windows and make creating and managing off-site copies of the data more difficult.

Data de-duplication can reduce backup data stores and save money, but with backup windows tightening and fewer people available to manage more data, keeping your backups recoverable and easy to manage should carry as much weight as the money companies stand to save with de-dup technology.

Copyright © 2007 IDG Communications, Inc.

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