2tb of usable space is not that much for mysql data. I have a 750 gig db personally and know people that have many tb's of mysql and hadoop data.
Also, I'd go with a desktop for database stuff any day. From what I've experienced, it goes something like this:
Fibre > iscsi > SCSI > ata > firewire > nfs > usb
I say that iscsi is faster than SCSI because I generally have 10GE iscsi and many more disks than I can throw in a proliant. And, I don't know why but fc just seems to work faster than anything else for db stuff.