Check the disk manufacturer web site.
A good diagnostic is not concerned with partitions or files. It
checks SMART, it checks sectors. Some diagnostics are read only.
If a diagnostic has an option which is DESTRUCTIVE, it will be
marked as such. At least one utility, has an option for write
testing. The one I use here, from Seagate, is read-only.
*******
If the disk is suspect already, you should have a backup. One
way to make a backup, is with dd_rescue. It can be used in two
passes, copying accessible sectors on a first pass, and spending
more time on a second pass. This is preferable in extreme cases,
to attempting to use other utilities - on at least one hard drive
I had here, each sector was taking an eternity, and I had to
stop copying because basically my attempt to copy the disk
would have taken forever.
http://www.cgsecurity.org/wiki/Dama...t_method:_Antonio_Diaz.27s_GNU_.27ddrescue.27
One advantage to a sector copy utility, is the head moves slowly over
the surface during the copy. File by file copying requires more head
movement, and a sick drive may not like that very much. Sector by
sector is a sequential access pattern.
Which approach you use, depends on how sick the drive is. If you think
you have time, by all means, try file by file methods. If it looks like
the drive will die, the next time the power is cycled, then you may need
another method.
Paul