(73 x 14 = 1022) x 12 servers = 12.264TB RAW 12264 - 5120 = 7144
This shows me you're wasting over 7 TB worth of storage since you cannot share it between servers. This is why a SAN makes so much sense for many companies. You'ill also need at least two more disks per server in your SAN to act as your mirrored boot disk. This means 24 more drives. Create 12 RAID-1 mirror sets in the array and dedicate one for each server. Do not share these disks with other servers, or install any other applications on them. Use LUN security in the array to make sure the server's host bus adapters (HBAs) have a dedicated mirror set as its boot LUN. Use LUN number 0 (zero) for each boot LUN, if your array supports it. You should use at least two HBAs per server but three would be better. I would dedicate one HBA per server as the backup path through the SAN fabric, which is either zoned out to a Fibre Channel-based tape library connected to the fabric, or to a third SAN switch dedicated for backup. You'll need at least two 16-port switches for the fabrics with each switch as its own fabric, and each server connected to each switch. It should end up looking something like this, which is from my book that shows you how to hook up server-free backup.
If you do use a third HBA in each server for backup, then you'd use another SAN switch and the dedicated backup HBAs and the tape library would connect to that switch. You'll need "path management" software on your servers so your data path can failover in case of the HBA, switch or storage controller fails. If this is a Unix solution, then something like Veritas DMP or Solaris MPXIO can be used. If it's Windows, you can use the MPIO driver, or you can buy software from your storage vendor that supports their array (Hitachi HDLM, EMC Powerpath, HP Securepath, etc.)
Click here for part two.
This was first published in June 2004