When to choose copper:

• Cost Sensitive
• Short distance between servers

Some info from wikipedia on copper technology

10GBASE-CX4 Technology.

It is designed to work up to a distance of 15 m (49 feet). This technology has the lowest cost per port of all 10Gb interconnects, at the expense of range.

10GBASE-T

A standard released in 2006 to provide 10 gigabit/second connections over conventional unshielded or shielded twisted pair cables, over distances up to 100 m.^[2]

Performance Question:

“Can I really achieve 10G/second between two servers connected with 10Gig Ethernet adapters?”