The problem with disk arrays is that they don't travel well. This can become a problem when developing an offsite storage strategy. It is not always possible to transfer large amounts of data from a local to a remote disk array due to network bandwidth limitations or budgetary constrains. In addition, depending on your organization's backup data retention policy, it can be difficult to accommodate long-term storage of backups or archives using only disk storage. Tapes are much better suited and cost effective for this type of application. A massive amount of tape storage can be kept in a vault with a fraction of the power requirements for the equivalent disk storage.
Generally speaking, it is a good idea to send as much backup data to disk as possible. But good old tape storage still has its place and use.
This was first published in March 2005