So I upgraded to 5 from 4.1 – Cool. Almost. Vanilla install had no support for my Promise SuperTrak EX-8654 card which I have in my HP MircoServer. Now what?!?!?
Well, after a lot of searches, the solution was actually on the Promise site! Yay for them!

So in short an example of you to load a driver on esxi 5.0.

1) Enable ssh access on your esxi 5 host (what do you mean you’ve already done that? It’s dangerous!)

2) Get you driver. The 8654 driver I got from the Promise support site was called 'scsi-stex-4.07.0000.75-1OEM.500.0.0.472560.x86_64.vib'. Yep, what’s in a name.

3) Copy over the driver to the host using scp
ex: scp <driver name> root@<esxi_5_host_ip>:/tmp

4) Next ssh to the esxi host, go to /tmp

5) Install the driver
esxcli software vib install -v /tmp/<driver name>

6) Reload the esxi host – Oh I hand’t told you? Well you need the driver right?

7) Then ssh to the esxi host and check if the driver loaded with 'esxcli software vib list'
In my specific case it looked like this:

~ # esxcli software vib list
Name        Version                             Vendor   Acceptance Level  Install Date
----------  ----------------------------------  -------  ----------------  ------------
scsi-stex   4.07.0000.75-1OEM.500.0.0.472560    Promise  VMwareCertified   2011-12-26


8) Sit back and enjoy the fact you have access to the disks again for adding as a datastore.