storage vendors have a credibility problem. i think the big
storage vendors, as referenced in the op, sell you on many
things you don't need for much more than one has to spend.
I went to a product demo from http://www.isilon.com/
They make a filesystem that spans multiple machines. They split the data
into 128k blocks and then duplicate store them across your RAIDs. They
claim over 80% utilisation rather than the more usual 50% of mirroring
http://www.isilon.com/products/OneFS.php
I'm no expert but after reading a bit of Shannon when I got back I found
it hard to believe their claims but they have great market penetration
because you just stick another multi Tb server in the rack and it adds
itself to the array.
All I kept thinking was "you want $100k for 25tb of aoe and cwfs, get
out of it!"