Depending on the actual size of the server's hdd,
which would indicate just how long the copy process would actually take,
what I would do is shut down the sever & boot the PC from a rescue-linux cd,
& run Gparted. Using that to perform a image copy disk - disk,
from the old/failing hdd to the new hdd, erasing anything on the new disk, in the process.
This would give a exact copy of the old disk & would also be bootable in the same way.
as the op is not linux literate, this way is a GUI & more achievable.
there are several how-to's, & this is just one:-
& this is a pictorial version :-
Note: the O/S that is being copied is irrelevant.