I have more then 10 years of experience in design, analyse and administering VMware virtual environments starting from virtual infrastructure 3.x to vSphere 5.x.
I have experience in drawing and designing virtual infrastructure diagrams with a complete redundancy at each level of Storage, Fiber Switches, ESXi Servers and Network Switches. In a fully redundant model, the availability of the servers are taken care at each level. If a path is broken in between, the servers will still have connectivity. This can be achieved by configuring the components like below.
At Network: We have to make sure all the ESXi servers are connected to at least two different physical switches.
At ESXi servers: ESXi servers generally comes with multiple network cards. We have to connect each card to a different switch. If we have more than or equal to 4 NICs we can configure ether channel at switch side which clubs multiple NICs and gives more bandwidth and redundancy for servers. NIC teaming also can be done on ESXi servers.
At Fiber Switches: We have to make sure all the ESXi servers are connected to each of the Fiber switch (Two Fiber Switches are required). The Multi-Pathing software on ESXi servers manage the LUNS allocated to the servers.
At Storage: Every storage comes with two controllers. We have to make sure each controller is connected to each fiber switch.
We can configure Alarams for CPU and RAM that will help us to find out resource constraints on the servers.