I'm setting up a VMWare ESXi 5 environment with 3 server nodes. Dell recommended 2x Force10 S60 switches shared (iSCSI SAN, LAN/WAN). The S60 switches are extremely powerful. They have 1.25 GB of buffer cache, < 9us latency. But they are very expensive (online price ~$15k per switch, actual quote a little less).

I've been told that "by the book" you should at least have 2 internal switches for SAN, and 2 switches for LAN/WAN (each with a redundant). I know some of the pros and cons of each approach. What I'm wondering is, would it be more cost effective to disjoin the SAN from LAN with less expensive switches?

The answer to this question highlights what I should be looking for in a switch for the SAN. What should I be looking for in a LAN/WAN switch, in comparison to the SAN?

With the above linked question for the SAN:

• How is buffer latency measured? When you see 36 MB of buffer cache, is that shared or per port? So 36 MB would be 768kb or 36MB per port?
• With 3 to 6 servers how much buffer cache do you really need?
• What else should I be looking at?

Our application will be heavily using HTML5 websockets (high number of persistent connections). The amount of data being sent is small; Data sent between client <-> server isn't broadcasted (not a chat/IM service). We will be doing some database reporting too (csv export, sums, some joins).

We are a small business and on a budget. We'd probably only be able to spend no more than $20k on switches total (2 or 4).