My feeling (And way of work) is to have a minimum of 4 ports, And usually 6 (2 ports are internal, and 2 X Dual-Port Nics. You can use Quad-Port but for greater redundancy + Price I use Dual-Port).

I usually have 2 Ports for SC on the MNG network, 4 for VMs and 2 for VMKernel storage & Vmotion. If no iSCSI or NFS is needed, I add the bandwidth to the VMs.

This also allows you greater flexibility (Put some NICs for failover), Higher bandwidth, Greater configuration options, seperation of networks (Security) and seperation of VSwitches (Bandwidth), and so forth.

Also, Remember the 32 Ports limit (If you ever reach it... but worth mentioning it)

-Sharon

Discussions and best practices apart , Practically also one needs to analyse .

Say you go with Recommendations of 6 -1 2 NICs . Consider 2 years down the line . Whne the number of ESX Server grows upto 50 ( For Example ) in a large organization

Will you be able to provide that many NIC ports from the Switches ?

50 ESX * 10 NICs = 500 NIC Ports

In a DC rack  , if you accommodate 10 ESX Servers you will need to vae60 ports

which i think is practically not possible .

Thats the reason we go with 4 NICs per ESX Server

Thanks

Sudharsan

VCP, MCTS ( Server Virtualization )

There are advantages and disadvantages using VLANs and you chose not to use VLANs so it requires extra NICs and 15 pNICs is very well architected with complexity involve, but I hope you will utilize VLANs if you're out of PCI slots   Anyways, with Nexus v1000 switches, things can change the way we design our virtual networks and matter of fact, a Cisco engineer just have to take care virtual networking configurations for ESX architect so we don't have to manage it them than that would make life easier.

For large enterprises, its worth the money spend on these NICs because it provide redundancy and enough throughput and security concerns.  If you're design for large enterprise systems with 4 pNICs and their fine with it than its okay, but for my clients it not sufficient but could be doable even with 2 pNICs but you have to decide the risks involved.

I don't agree with 2 nics being enough for a scalable cluster, we have 8 per host. BUT 4 of those are due to old security restrictions that certian subnet's have to have a dedicated NIC, vlan trunking was not enough. That being said we have 6 different vlans running into 2 nics, iscsi using 2 nics with etherchannel. the rest have the standard config.

But as with anything depends on your needs, but with trunking and etherchannel, 4 is a good number.