[Beowulf] High performance storage with GbE?

[Bill Broadley]

Sorry all, my math was a bit off (thanks Mike and others).

To be clearer:
* $24k or so per pair of servers and a pair of 15*750GB arrays
* The pair has 16.4TB usable (without the normal 5% reserved by the
   filesystem)
* The pair has 20.5TB raw  (counting disks use for spare and redundancy)
* Each pair has 22 TB marketing (Using TB = 10^9 instead of 2^30)

So 7 servers could manage to provide the mentioned >= 100TB.  Total cost of 
7*$24k=$168k.  Total storage cost does not include the GigE switches, 10G 
uplinks, nor 10G nics.  Usable capacity of 7*16 = 112TB.

The above config assumes that software RAID performance = hardware RAID
performance or that the Dell MD-1000 can allow 2 masters access to
all 15 disks (not at the same time).  I'm not sure that either is true.

 From the scaling numbers I've seen published with PVFS2 and Lustre seems like
it should still be possible to manage the mentioned goal of 1.5-2.5GB/sec
(which assumes 220MB/sec or 440MB/sec per file server pair for 7 pairs.)