Tiered storage is an underlying principle of ILM (information
lifecycle management). It is a storage networking method where
data is stored on various types of media based on performance,
availability and recovery requirements. For example, data
intended for restoration in the event of data loss or corruption
could be stored locally -- for fast recovery -- while data for
regulatory purposes could be archived to lower cost disks.
Today's tiered storage infrastructures range from simple two-
tier architecture consisting of SCSI or fibre channel attached
disk and tape to more complex infrastructures, which in some
cases are comprised of five-to-six tiers. Regardless of the
number of tiers, organizations are looking to tiered storage and
ILM to lower cost and improve operational efficiency.
Implementing tiered storage infrastructures can dramatically
decrease the cost associated with achieving an RPO and RTO of
zero. Classification of data can provide different RPOs and RTOs
based on application and business requi