Consider this: I buy a little NAS, e.g. some Synology with 4 bays, put 4 CMR drives in it, configure it for RAID-5 for covering the case of one failing drive, and let it do its merry business running.
Just so that I can act quickly, should, at some point, one disk in the RAID fail, I'll buy a few hard drives of the same type, and lay them to rest on the shelf. (perhaps more than one, as, if one drive in an array of ~ same aged ones fails, it might indicate other may follow soon?)
Will a merely stored drive age considerably (electrolytic capacitors or so?), so that it would (nothing else considered) be more economical, long-term wise, to buy only when needed? I am not talking of magnetic degrating of data - but empty drives, kept as drop-in spares.
