In my last column I discussed how what we used to consider active data is changing. We now have to look at the potential working set instead of the actual working set. Thanks to initiatives like real-time analytics, some data that we used to classify as archivable now needs to be at the ready. If this is the case, what is the role of archive? How do disk and tape archives participate in an increasingly active world?

The key to a balanced storage strategy, even with all this active data, is to change how we decide to archive a certain set of data. Under the current archive methodology the most common decision point was last modification date. In other words, data that is X days/years old can be archived, everything else has to stay on primary storage. The problem with this methodology is it is not compatible with real-time analytics and not even really compatible with the way users use data.

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http://www.informationweek.com/storage/data-protection/active-data-vs-active-archive/240154236