All,

I apologize in advance if this topic has been covered.  I looked through
the archive using a variety of search terms without successful results.

We have determined that a 4 x LTO3 tape library will work well in our
environment.    Our Sun SEs, however, claim that attempting to drive such a
library with one host (i.e. where all four LTO3 drives are fiber-connected
through a switch into the server) is asking for trouble and that we really
must consider driving it with two, in order to split up the gigE network
bandwidth requirements as well as the FC HBA bandwidth requirements.
Their argument seems to be based on the theoretical maximum sustained I/O
that a Sun server backplane can handle, at 1.2 GB/sec.

What I'm not understanding is how one calculates I/O across a server.
Given that a server takes network traffic (input) and routes it to the tape
drives (output), is it accurate to basically double the aggregate
write-rate of a bunch of tape drives (read and write) and then double that
number again to factor in performance with drive compression ?

My head is so full of numbers and stats at the moment that I cannot think
straight and I need some help.   Thanks!

-ty

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