I have two datacenters (DC1 and DC2) with a SAN switch in both. Both SAN switches are attached through FC. Data is in complete sync. No issues.
Now I want to connect blades in my chassis in both DC1 and DC2. I have empty ports in SAN switch. Can I use empty ports of SAN switch or I have to install separate LAN switches?
If we talk about theory and conception. Yes you can it is convergend technology. If your swithces can support it is. Sorry but your question is not correct. Because we don't know your switch vendors (Brocade, Cisco or etc ...).
You can read this Brocade VDX 6730 Converged Switch for IBM or Cisco Revives LAN-SAN Convergence Play in the Data Center
Practice: Majority of those that I saw, san switches in blad-chasis not supported convergence technology and you need to check your switches.