4 May
2025
4 May
'25
5:33 a.m.
On 4/05/2025 6:46 am, Brian Knittel via cctalk wrote:
Passing on a request: anyone know of a way to erase
user data off a Mac SE hard disk that will leave the disk and Mac OS intact? The machine
works and could go to a new home but has privileged medical data on it so just deleting
files isn’t sufficient — the free space has to be overwritten. Are there any utilities
available on floppy disk that could do it? Plan B is taking a sledgehammer to the drive,
but seems a waste to go right to euthanasia if there’s another option.
As a few others have pointed out the easiest way to erase files to they
can't be undeleted using a simple utility is to delete them and then
fill up the disk with a large file containin zeros. Or simply keep
copying an existing inocuous file until you run out od disk space (not
difficult if you copy it, then copy both copies and then all four, eight
and so on.
It works on all systems.
HOWEVER this does not destroy data to the point where people like me
can't possibly recover anything given enough time and incentive. Don't
assume this is good enough for security sentiive infomration.
I won't go into the details (buy the book!) but one easy example is data
on bad sectors that have been mapped out and marked "do not use" by the
OS, but are very likely still readable if you try hard.
I suggest a balanced view. Is anyone going to spend time and money
trying to recover the deleted data, and if so, how much? Unless it's a
lot of time and money then deleting the files and zeroing the empty
space is probably good enough.
Regards, Frank.