Comment by pmontra
15 hours ago
HDD can be written multiple times with random data if data centers really have to protect what their former customers wrote on them. I never looked at those details in standard contracts.
There is also encryption at rest.
I wrote hddrand to write random data and optionally read it back to verify integrity. https://github.com/mqudsi/hddrand
When I used to do computer refurbishment, 'Boot and Nuke' was great for this. Load it up at boot, and write over the with random junk a few times.
All you really need to do is write one pass of zeros on them. That will prevent anyone but a very dedicated adversary with expensive equipment from recovering any data, especially on TB scale drives.
Can still take hours per drive though, which is why a lot of people skip it.
Or encrypt it and just trash the encryption header.
I make a random 1MB chunk, then write that all over the drive, at overlapping offsets. I've been told that really clears it. On IDE-spinning-rust disks I trusted it, not sure if I should trust these modern SSD
Why rewrite the same 1MB chunk, instead of making new random chunks?
Redundant data at least opens the possibility that the drive could deduplicate.
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All the large datacenter/cloud companies do not let hard drives leave the building.
They have enough investor money they don't need to recoup it selling used drives. Straight to the shredder.
> HDD can be written multiple times with random data
Which costs more in compute than simply throwing the drive in a shredder
What's the disposal method for shredded drives?
Mount Doom
Not really, if we give the HDD some resale value. There's a market for used but functional hard drives.