There are many ways to do what we call two-stage backup. Two-stage backup is where data is backed up to a disk based on business requirements for being able to recover data for an application and backed up to tape from the secondary storage device on a different frequency that is based on the company policies for data protection using offline media.
Backing data up to a SAN can be done many ways but we've seen the most effective solutions usually take a point-in-time copy (snapshot, etc.) of the data in conjunction with the application operation (database quiesce for example) and then data moved to the secondary storage device which is typically a less expensive, lower performance storage system (some of the new ATA-based systems are targeted for secondary storage). Backing that data to tape is done with one of the popular tape backup software programs. Some of the tape software programs have the ability to backup to disk but usually put the data in tape image that reduces the flexibility and efficacy of a selective restore operation.
Using a NAS as a backup target requires some specialized software such as NeApp's SnapVault. You might run into some issues with backing up LUNs to a NAS using a remote file system so you need to look into your requirements and whether those types of backups can meet your needs.
Evaluator Group, Inc.
Editor's note: Do you agree with this expert's response? If you have more to share, post it in one of our .bphAaR2qhqA^0@/searchstorage>discussion forums.
This was first published in April 2003