We are buying a second server so in case of a HW failure we can simply switch over the HDDs and continue. My question is how similar does the HW have to be so this works? Also will it require reactivation? Could the processors be different? How about the memory configuration both amount and type (unregistered vs registered). The rest we should be able to match, i.e. Ethernet, integrated raid, etc.
Even better would be if we would have a "shadow" server that automatically synchronized everything incl. SQL data, etc. Is there something like that?