The life cycle of data

Like hierarchical storage management before it, information life-cycle management uses a tiered approach. But HSM moves data based on age alone while ILM determines tier based on business value.

Tier 1: The most expensive media, such as EMC Symmetrix or Hitachi Lightning, stores data generated by business-critical applications. As the data ages or becomes less valuable, it moves to Tier-3 storage.

Tier 2: Less-expensive secondary storage, such as EMC Clariion or HP StorageWorks, holds information generated by front-office applications such as Microsoft Word.

Tier 3: Represented by inexpensive Advanced Technology Attachment drives and EMC’s Centera, Network Appliance’s NearStor or StorageWorks’ BladeStore, this tier houses fixed-content data that doesn’t change or is accessed less frequently.

Tier 4: Tape libraries, such as Storage-Tek Tape Library, archives aged data that is reaching the end of its corporate usefulness.

Tier 5: An offsite tape archive might house data with little value but needed for historical reasons or to support litigation.