[Roald Hemel]

You could use somtehing like this:

https://sonnettech.com/product/rackmacminixserver.html
or:
https://sonnettech.com/product/thunderbolt/index.html
or:
https://www.promise.com/storage/raid_series.aspx?region=en-global&m=192&rsn1=40&rsn3=49

If you combine a Sonnet Rackmac Mini Xserver (with decent 4x1Gb/s Ethernet card in PCIe slot) and the Promise SANLink to connect to your fiber swith, the Mac mini server could replace a Xserve.