A reader posed the following question recently to our SAN expert: Christopher Poelker:
You talked about disk compatibilities, anything about tape? Would there be any reason for not sharing AIX, Solaris and NT2000 to the same tape drives in a SAN fabric as long as they are zoned to see the tape drives but not each other?
Would the tape drive sharing be controlled by SSO software provided by Veritas or virtualizing tape drives with technologies such as StorageTek's SN6000?
Here's Chris Poelker's answer:
He who controls the robotics, controls the library. When using a central tape library for SAN backup you should choose a backup software vendor that has the capability to do cross platform backup. Usually, the SSO (shared storage option) option is for homogeneous environments./p>
Either every SAN connected server runs its own backup engine and the "master" server doles out access to the robotics, or one dedicated backup server attaches to image copies in the SAN and the backup server backs up the client server volumes to a SAN connected library.
In your situation, without image copies, you would use three backup engines (NT, Solaris and AIX) and use switch zoning to "turn on" tape access for each environment so the clients can get to the tapes and the robotics in the library.
If you take advantage of image copies, you could get by with less licensing costs and just mount the client volumes from a single backup engine as long as the software is familiar with all the OS file systems you have.
An alternative method would be to use the SCSI extended copy command (E-Copy) to do cross platform backup to a shared tape resource. E-copy provides "serverless" backup where the data path is directly from the client disks to the tape library without ever hitting the backup server, except for IP metedata.
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 May 2003