Hello, I'm planning to move my 5.1 servers to 6.5 this year (possibly
looking at Linux later). All my servers are using TFS. Are there any
gotcha's in doing an upgrade from 5.1 to 6.5 on the same server? I guess I
need to make sure the server is compatible driver wise, enough disk space
(any ballpark %-wise for the upgrade process?).

I'm asking at this point as I have a 5.1 server that will need more disk
space soon, and for various reasons it'll involve a re-install of the NOS
because I'm changing out the drives in the RAID array. I don't mind doing
this, but I don't want to have to do another re-install a few months later
when upgrading to 6.5.

So I guess my question is, is the general recommendation when upgrading from
5.1 to 6.5 and keeping the same hardware, to:

a) do an in place upgrade
b) backup, wipe, install 6.5, restore