Cleaning up an HDD (removing deleted files etc before PC disposal)

[Steve Firth]

Not really. The data still recoverable for FSVO of "recoverable". Mechanical disintegration has to reduce the drive to dust to be useful for this you need a hammer mill.

[Steve Firth]

That's stupid advice.

[Steve Firth]

See my previous comment about exaggerated fears. Once a drive has been overwritten with zeros the costs/effort of recovery of data make it unlikely that anyone will bother unless they suspect that there is something of real value on the drive. And by real value I mean major industrial espionage or government data.

[Andy Burns]

So in one post you say overwriting is good enough (because the spook recovery techniques are exaggerated) in the next post you say physical damage with a hammer is not sufficient ... you can't have it both ways.

For domestic purposes I'd say a single overwrite is sufficient.

[The Natural Philosopher]

well,l steve firth is a well known wanker, so I wouldn't pay too much attention to anything he says.

IBM merely require the discs to be crushed. That is what the insurance requires and that is what they do.

Most of the machines are crushed with them, as the cost of stripping the drives out and recykling the rest is not worth what the chassis are worth.

Top end stuff does get stripped tho.

overwriting each block is enough to defeat all but the NSA, which ought to be good enough for domestic use.

[Steve Firth]

Correct.

No, in another post I reply to a post stating that a hammer is the "Safest way" to destroy data, it isn't. You seem to be having problems with basic English comprehension.

I don't need to have it both ways since each way was different and each represented a different issue.

So would I, in fact I did.

[Clive George]

I'm reminded of my ISP who broke their main email store by having an idiot hit "wipe" (or similar) on their live array rather than the one he should have done. This counted as a sufficiently major cockup that the disks went off to a specialist recovery firm, who after several weeks decided they could do nothing.

[Steve Firth]

A lot of it is a case of "beyond economic recovery" and as areal densities increase on HDDs the "beyond economic recovery" window moves. At one time tracks were wide and the uncertainty of head positioning such that a skilled computer scientist could create heads that, in a clean room environment might just pick up some remnant of the former data in an area of uncertainty to one side or other of the data track. Now tracks are thinner, heads reaching towards theoretical limits of performance and the room for lashing up some rig to capture data isn't really there.

As I mentioned before simply using dd as in:

dd if=/dev/zero of=/dev/sd bs= count=

will work adequately for domestic use.

Some tuning of block size can speed things up immensely.

[Andy Burns]

If application of the hammer bends or breaks the platter at all then you're back to needing spook technology to retrieve any data from the bits (rather than your dust)

if the hammer merely damages the electronics, then yes a cleanroom outfit could transfer the spinning bits into a donor drive and retrieve data from it, but the cost would still be in the hundreds, so unlikely to be a problem for "domestic" security.

In what other way are you imagining the hammer being used?

[Steve Firth]

You seem to be misunderstanding the term "safest" which is different from the word "adequate". I'll try to explain it to you:

One pass writing of a disk with zeros is "adequate". It will destroy data to the extent that any recovery will be expensive, time consuming and not possible without significant resources. If the disk is examined it will not present obvious evidence to anyone that there was every anything of value on the disk.

Clonking the platters with a hammer is "adequate" the disks will be rendered unreadable to about the same extent as above.

In both cases it is possible that someone with sufficient knowledge, time and cash could reconstruct data from the disk. Such a person would be most likely to be a government employee, probably working for a foreign government.

The term "safest" indicates destruction of data to the highest possible standard. Clonking with a hammer does not meet the criteria for "safest" destruction of data on a disk. There are national and international standards for the safest destruction of data on disks. For mechanical destruction the standards specify destruction in a hammer mill or ball mill and require the disk to be reduced to dust before disposal. An alternaitve is smelting the disk which can be done in small open hearths using a propane torch or in industrial smelting plant.

I hope that you now understand the meaning of the word "safest" which seemed to be escaping you up to this point. You were focussing on what seemed important to you (bash it with a hammer) and not on the actual meaning of the words being used.