Updating ESX 3.5 to latest version

[hcpitadm]

I have a quick question in regards to updating some servers that are out of date and need to be updated to ESX 4.0 onwards

Two ESX boxes:

1) 3.5.0 82663

2) 3.5.0 123630

I realise these are very old so what would be the best way to update these. I've tried vSphere client and it said it can't do it. I've tried the older client and it can't do it either as it's not supported as well? I have downloaded the ESX3.5U5a zip and tried to load it into the update host utility and it says invalid file. Not sure why as I would assume you can go straight to that version. I'm trying to update these two hosts from a Win2008R2 64bit Server. Any tips to get these updated safely/easily? I'm using vCenter 4.0.0 to manage these two hosts.

If I manage to get this upgrade done, do I have to worry about any licensing changes? We are licensed for vCenter 4 Foundation

Thanks

[schepp]

You have to convert your Infrastructure 3 licences to vSphere licences in the vmware licence center. Fairly easy and well explained on that site.

If you got vCenter 4 (there are later versions like 4 U1, 4.1) you can only upgrade your esx host to 4 as well (and not 4U1 or 4). Download the correct iso or zip file from the vmware page (choose version history to get the right one for your vcenter), load it into your VUM and there you go.

Regards

[hcpitadm]

Ok, this is confusing

So would I be better to:

go from my current 3.5.0 to 3.5U5a then to 4.0 then to 4.1

or

Can I convert my 3.5 licenses to vSphere 4 ( I'll assume they are ok for 4.1 ) then update to 4.1 from there?

Can I even go from my current low patch level straight to 4.0 or 4.1? my vCenter is 4.0.0 so I'll again assume I'll have to download the 4.0.0 ISO, use that to update the server to 4.0 then download the 4.1 ISO and update vCenter to 4.1 and then I can update the servers to 4.1 as well?

Or am I reading that incorrectly? Such a hard process to do one thing

Thanks for the help this far!

[schepp]

You can upgrade your vCenter to 4.1, convert your ESX/ESXi licences to vSphere (4 and 4.1 are the same licences), download the 4.1 iso of ESX, load it into VUM and upgrade the Hosts.

Didn't test the step from 3.5 to 4.1, only to 4.0 but I think to 4.1 it should work too.