I need to upgrade storage in a PowerEdge T420 (page 24). The server has 8 slots for hot swap disks and 4 for cabled disks. My question is: Will ANY (Dell,Western Digital, Seagate, Maxtor, Toshiba, Refurbished) 3.5' SATA hard drive work? Do I need to look at any other specs of the disk/server for compatibility besides the SATA interface itself? (and besides being hot-swap or non hot-swap, of course) I reached out to Dell support in order to know if there's a limit in the amount of storage space to upgrade and they told me there was no limit, but this document lists "maximum internal storage" as 32TB. Does this refer to another kind of storage or the support guy was wrong/sleepy? Also, in the upgrade of a HP Compaq DC5850 Microtower, same question: Will ANY 3.5' SATA cabled hard drive work? and, can I unplug the optical drive and install 4 SATA hard drives? Thanks in advance.