If your storage array has the capability to do snapshots (for example BCV, ShadowImage, Clone, etc.) then the SAN connected backup server can connect to the snapshots and back them up on behalf of your application servers. You would need to alter your LUN security in the SAN to allow the backup server access to the snapshot LUNs. If you alter LUN security to dedicate some snapshot resources for access by both the application servers and the backup server, you can rotate the snapshots between application servers for each backup job. This may require some manual co-ordination on your part.
All backup streams will travel from the snapshot disks, through the backup server, to the Library connected to the backup server.
If the tape library is directly connected to the SAN, then it makes things a bit simpler. Using the shared storage options for your backup software, backup can be automated to allow each individual application server to share the SAN connected tape resource. The backup server simply co-ordinates the use of the library robotics, and the application servers themselves handle the backup streams to tape.
Therefore, the advantages of SAN connected shared tape resources are:
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This was first published in November 2003