disposing safely and securely of unwanted computer equipment?

[Howard]

On modern hard drives, the density of the data is so high that the chance of reveiving previously written data is virtually nil. However, on older hard discs, where data is less dense, a paper written in 1996 by Peter Gutman, a computer science professor at Auckland University in New Zealand, suggested that data could be recovered from disc sectors that had been overwritten. The idea behind this is based on the fact that the read/write heads are never precisely positioned over the same exact area twice and that by using statistical analysis techniques, and in some cases, electron-microscopes it would be possible to find a 'shadow' of the previously written sector.

As I said, more trouble than it's worth and filling a disc up with random files, or using a "live CD" to do a secure erase (http://www.howtogeek.com/howto/15037/use-an-ubuntu-live-cd-to-securely-wipe-your-pcs-hard-drive/ is perfectly fine. Of course if you are really worried about it, then hit the disc with a very large hammer or drill a hole in it!

[marveld]

Howard wrote: "It would be more trouble than it's worth to get anything off it that was "under" the video files".

I'm curious. From my basic understanding of hard drives / files, you can't have data "under" other data. Sure, data from a file can be in several separate areas of the disk. These file segments are recorded in the FAT (File Allocation Table). When you delete a file, the FAT is updated to indicate the areas occupied by the file are available once more. If you then populate ALL these areas with new data, the old data is overwritten. To be sure you've covered all the space previously occupied by a sensitive file, you would need to fill the entire hard disk with new data (well, that's the method I was adopting).

Is my understanding correct Howard? Please explain your "under" terminology. Thanks.

[tonyjones]

Kim Hollings will take any unwanted old computers or parts for making into new computers for free distruibution within the Parish or one of the Computers in Africa charities.  Tel 07831 541 245

[Howard]

It would be more trouble than it's worth to get anything off it that was "under" the video files. I think you'll be fine.

[marveld]

I've got an old USB 1 style external drive that I am giving away. I cleaned it up by formatting the drive and then totally filling it up with video .VOB files that will overwrite the space that might still be occupied by my sensitive data. I reformatted once more and I think it should be ok. Anyone disagree?

[Howard]

I have manually deleted all the data from it and now want to 'get rid'. I have done a few searches to try and find a local charity / organisation that might want it, rather than me taking it to the tip but come up with nothing useful for individual disposals. The council website isn't very forthcoming either. Does anyone have any any advice for either
A) passing on the equpment to a reputable organisation who can wipe the hardrive and reuse the equipment
or
B) Safely removing the harddrive and taking a hammer to it (I seem to think that computers still keep an internal charge even when disconnected?)

Alison, just because you have deleted the data doesn't mean that it's gone. In fact, it's probably very easy to recover it. If you want the data to be unrecoverable but the hard disc to still be usable then you will need a bootable disc (flash, floppy or CD) with a secure erase utility on it. This then spends several hours writing and rewriting random data over your disc.

You have to have a certain amount of IT knowledge to make one of these discs yourself or otherwise someone else can make you one. If you give the PC to charity then you need to ensure that they will "scrub" the disc using this methodology before they rebuild the PC.

The other way is physical which is either degaussing with a strong magnet (which deletes the low level formating) or smashing it with a hammer or drilling through the casing to the other side.

[alison]

oh that sounds promising - if you have any more details in a couple of weeks let me know, I won't take a lump hammer to it until then!

[tonyjones]

There is a gentleman who 'advertises' in GLOOT (God's Loot issued by All Saints Church) for people to give him old computers so he can salvage bits to make workable machines for charities etc.
The next issue comes out in a couple of weeks.

[alison]

Hi

I have have a computer processor that has been replaced. I have manually deleted all the data from it and now want to 'get rid'. I have done a few searches to try and find a local charity / organisation that might want it, rather than me taking it to the tip but come up with nothing useful for individual disposals. The council website isn't very forthcoming either. Does anyone have any any advice for either
A) passing on the equpment to a reputable organisation who can wipe the hardrive and reuse the equipment
or
B) Safely removing the harddrive and taking a hammer to it (I seem to think that computers still keep an internal charge even when disconnected?)

All help gratefully received, either via here or PM me

Thanks

Alison