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Comment by pmontra | Hacker News Reader

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.

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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.

Cause making new random was taking too much time.

Pretty sure most modern computers can generate random data faster than they can write to a disc.

All the large datacenter/cloud companies do not let hard drives leave the building.

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.

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.

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