User:River/Storage

Small:

Two servers, two arrays. Each array can be RAID-5, with the server mirroring across each. Can lose one server and one array without downtime. Small arrays are reasonably priced (e.g. Sun 25xx). Once the array's capacity is reached, more can be added, limited by # of host ports (typically 4 at most).

  server   server
   |    \ /    |
   |     X     |
   |    / \    |
  array    array

Large:

Any number of servers connected to an FC fabric (two redundant switches), then connected to storage. Can add any number of hosts and arrays up to the switch capacity. More switches can be added.

  server       server  ...
    \         /
     FC fabric
    /         \
  array        array ...