Does USB key speed matter with ESXi 4.0

ESX and ESXi can't see individual volumes larger than 2TB which you have to bear in mind. There is some useful discussion on this with regard to ESXi and Dell servers in this VMware Communities thread. The 2TB limit stems from the fact that even with V4 both ESX and ESXi are still constrained by SCSI2 limits. If you build a RAID pack that is bigger than 2TB you will have to split it into volumes that are smaller than 2TB for ESXi to be able to use them. Note that this 2TB limit also applies to the maximum virtual disk (VMDK) size that ESX\ESXi can currently present to a VM but that's probably not an issue for you at this stage.

The simplest way to add storage in your case is simply to add the drive and then rescan the storage adapters (Under the Configuration->Storage Adapters Tab select Rescan). This should then allow you to create a new Datastore on the new drive (under the Configuration->Storage Tab select the Add Storage link and then select New VMFS Datastore). The downside of this approach is that you are creating silos of single drive Datastores which isn't good for resilience or performance.

If you have a RAID controller in the T310 then you should be able to configure RAID using the RAID BIOS at boot (CTRL+C to get into the SAS6/iR BIOS if you have that , CTRL+R if you have a PERC, see below if you have neither). That will allow you to build the RAID pack from the drives you have attached but your options will depend on the type of controller you have. You can then carve that (again in the Controller BIOS) into a number of smaller volumes so ESX can detect and use the storage. The problem with this approach is that you will probably need to reinstall ESXi completely to take full advantage of it but it's a much better way to present storage to ESX\ESXi.

Dell's RAID controllers have some limitations and in order to implement a hardware RAID5 your choices are limited to the PERC-6i, H200 or H700 controllers. The SAS 6iR only supports RAID 0 or RAID 1. If you want other options you'll have to buy a 3rd party controller that is compatible with both ESXi and the T310. The VMWare Hardware Compatibility Guide is useful for finding this sort of thing. The Community Support site lists things that are not actively supported but have been reported to work.

What device is that actually presents your single public IP? if it's a router then you can either move the ESXi's management ports from 80/443/902/903 to something else or advertise your own service to a non port 80/443/902/903 block and let the router just NAT them. If it's your actual ESXi box that's running the IP then you're out of luck, its management interface will own the IP and won't allow guest traffic over it - although it will happily share a single NIC - that's how the router/NAT method works. You could always buy more public IPs of course.