An input parameter (environment variable and possibly cmdline option) to
specify the max disk size to wipe, would avoid accidents like erasing a big
SAN or NAS that is connected to the wiped node. A sanity check, really.
The input parameter could be something along the lines of
Where N is an integer, and suffix is either empty (to indicate bytes),
or a unit to indicate kilo/kibi-bytes, etc. It would be good to support
at least B (for bytes), K[B], Ki[B], M[B], Mi[B], G[B], Gi[B], T[B], Ti[B],
and maybe even P[B], Pi[B]. Disks smaller than the specified size would
be eligible for wiping.