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The average enterprise today uses just 10% to 15% of its raw data center storage. This equates to 20% to 30% of usable disk space once necessary elements like RAID, replication and sparing are taken into account. This number has actually fallen somewhat since I wrote about storage utilization back in 2003 (see "
The low-utilization trend is hard to stop. Migrating servers and data to a new model is incredibly complex, risky and time consuming. For this reason, many businesses have decided, after a utilization review, to ignore the problem in existing systems and focus instead on new allocation. But even if a company institutes radically more efficient processes for allocating storage, it would take years to refresh enough of the estate to make much of a dent in the overall utilization rate.
Of course, there's justifiable growth in storage demand. But duplication is another factor. Mirrors and replicas were once exotic techniques used only for the most critical data, but they're common today. It's not unusual for a file to be mirrored for redundancy, again for backup, a third time for testing or decision support, and to then be sent offsite for disaster recovery. One company I know routinely keeps six copies of most production data online and dozens more on tape.
Combine low utilization with natural data growth, multiply it by duplication and it's an equation for disaster.
This was first published in August 2006