It's not great at the bottom end, either: 64TB raw for $96,000

Get a 24 x 2.5" 2U server, 3 8 channel SAS controllers, and 24 1 TB SATA SSDs. $15k or so will buy that. 3 of them are 72TB for $45K, so less than half the price, and certainly capable of saturating any network you can afford to run. Of course, if you just need 24TB, you can just buy one of the smaller machines.

You can fit it in one 4U machine with 72 x 2.5" disks for less money, but also less disk I/O, CPU, RAM and network bandwidth.

Is this "Big Data"? No, but neither was their 64TB config.

I wouldn't run nexenta any more, but your setup has no HA and no support.

You can run 3 x 24TB as a cluster, built for $45K, and get HA/failover... You can still run SmartOS/Illumos and ZFS for that matter... You should also be able to use any number of databases (Cassandra, RethinkDB, Cockroach) on there.

$1.50/gbyte is a huge premium over the price of lower end enterprise SSDs (which should be the dominant cost for this sort of thing).

SanDisk didn't give any technical specifics that I could find, but for comparison an Intel S3510 SSD is around $1.00/gbyte. At the higher end, it is around $1.60-$2.00, so I suppose they could be using fancier SSDs that would justify the price per gbyte.