Network connectivity Server disk array?

Depends on the type of load and disc used. For random reading can be cases when it will not give 300 Mbps with clogged completely Orami.
\r
Secondly, 4GB is the entry channel of FC to the receiving host. What the host does with the discs and what he is bringing into the network are very different things, because a lot of intermediate buffers.
\r
In General, you have the theoretical limit of the bandwidth of the FC link, and you're asking about the bandwidth of the Ethernet channel which will be connected via an intermediate server. There are too many uncertainties between them. Testrite.

iSCSI over 10G Ethernet optical link?
And you are sure that the array will operate at the speed of 4G? What kind of array?

FibreChannel 4гбит/c, the network will be the server issue.

Ask a question. Who and where must issue 4Гбит?
Here are a lot of factors, type of massive, cache size, RAID type, number of HBA... but ine do not measure the performance of the disk operations in gigabits (Mbps and IOPS).