I think the scheme is quite common: one disk storage and multiple frontends that access it simultaneously. Under disk storage understand not the shelf, and the conventional machine with lots of disks and created them FS. For example, there leiah website files and several machines with php-fcgi actively work with them.
Question: what is the best way to implement this? In what direction to look?
iSCSI, as I understand it — is not about that?
NFS? How is he with his performance at high loads? What are the pitfalls?
Can be better suited kind of network filesystem? What do have in this area?
The minimum task: parallel access rw + support groupqouta.
The task of the maximum: the ability to change the size of the shared space on the fly.
If it does something, and the store and its customers — recent freebsd, all this is under VMWare ESXi.