Some backup software vendors attempted to solve the cost problem by allowing a single library to connect to multiple hosts. If you purchased a large library with multiple SCSI connections, you could connect each one to a different host. This allowed you to share the tape library but not the drives. While this ability helped reduce the cost by sharing the robotics, it didn't completely remove the inefficiencies discussed earlier.
What was really needed was a way to share the drives. And as long as the tape drives were shared, disk drives could be shared too. What if:
A large database server could back up to a locally attached tape drive, but that tape drive could also be seen and used by another large server when it needed to back up to a locally attached tape drive?
The large database server's disk could be seen by another server that backed up its disks without sending the data through the CPU of the server that's using the database?
The disks and tape drives were connected in such a way that allowed the data to be sent directly from disk to tape without going through any server's CPU?
Fibre Channel and SANs have made all of these "what ifs" possible, including many others. SANs are making backups more manageable than ever - regardless of the size of the servers being backed up, In many cases, SANs are making things possible that weren't conceivable with conventional parallel SCSI or LAN-based backups.
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