Re: How to zero a failing disk drive before disposal?

On 2024-10-10 12:57, Ronald F. Guilmette wrote:

> Any suggestions?  If worse comes to worse I guess I will end up writing 
> my own tiny
> little C program to just write 4KB blocks to a designated output file 
> while ignoring
> all output errors, but I don't want to reinvent the wheel if somebody 
> else already
> created something I can use in this context.
> 
> Suggestions welcome.

I spent many years dealing with forensics and disk drives, as well as 
writing about the technology in 1980s and 1990s. My take is this:

If you want to pretty much guarantee nothing can be recovered, drilling 
a hole through the platters is the easiest way. Getting data off the 
undamaged cylinders once you've done that requires serious money and 
expensive equipment. If you want to go further, take the top off and 
bend the platters. After that you'll need an electron microscope and a 
lot of time to get anything back.

Don't bother with a software erase alone. Modern drives lie to the OS. 
They'll almost certainly have data on blocks they'll pretend don't exist 
as they're presenting a "perfect disk" to the OS, but data on such 
blocks can be read it other ways by transferring the platters out.

This was all true until Flash-EPROM appeared in hybrid drives. If you've 
got one of these, drill through the flash chips on the controller 
(again, Flash-EPROM presents as perfect so bad hidden blocks may contain 
useful data). If you're not sure which chips contain flash, drill-them 
all.

I'm aware defense erasure standards go further than this, but I regard 
them as over-paranoid unless the data is of interest to a nation state 
with an unlimited budget and plenty of time.

As to erasing old hard disks for re-use, the same applies. Don't rely on 
a software erase if it matters that someone could retrieve fragments. 
However, if you've been encrypting sensitive data (as you should), all 
they'd get is impossible to decrypt fragments - no problem.

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25-Sept-24 My apologies to everyone who I appear to have ignored for the 
last few years. A procmail script was misfiling some replies to 
Questions to the wrong folder.