Deleting files without trace

[#1]

I bought a new external hard disk which is faulty - constant message "device hardware fault".  I have to return it to the vendor.  However, it contains confidential data which I dare not release under any circumstances.  How can I delete files which I did manage to copy onto the external disk before the problem ?  The disk will not allow me to re-format it, no matter how hard I try.  I can remove files one by one, but I fear that they are only marked as deleted, and that they are still there and could be recovered by someone unscrupulous.  Is there any way to delete files permanently without re-formatting ?

I would be very grateful for help on this.

[#2]

You could try downloading the free version of Ccleaner and using it's Drive Wiper option. I have never used it but it's free!

[#3]

If it keeps on coming up with 'device hardware fault' then the OS shouldn't be able to read or write to it - or does that come up part way through a process. It does depend on what the actual fault is that is being detected. Could it be a cable fault? Have you tried using it on another OS i.e. Linux or even another computer? I've known Linux to read drives where Windows will not. But what seems strange is the fact you say you can remove files one by one. I wouldn't expect you to be able to do that with a drive fault. Have you still got ownership of the drive (under the security tab in properties). When you say 'remove' is that deleting them or moving them to elsewhere? Have you been to the drive manufacturers website to see what tools they have available to check the drive for errors

But I suppose it does come down to how much the drive cost originally and how much are the files worth to anybody else. I have in the past got out my trusty club hammer and just smashed a HD to bits. Nothing to read by the time I've finished. HD's come pretty cheap nowadays anyway. 

[#4]

There is a free windows program called eraser available from heidi.di if memory serves.

Failing that, open those files in notepad and replace all the existing content with random key taps - but make sure that you have more / equal key taps. You can copy / paste if you need to.

[#5]

Ideally you'd want a program which overwrites every part of the hard drive, ideally with zeros or ones.

Doing a bit of research, (well okay I cheated and typed some words into a well known search engine 😀 - hands up 🖐) there are numerous free utilities to completly wipe your drive.

You'll need something like that, just deleting files doesn't actually delete them. It just updates the drive FAT (file allocation table) to think it is and marks the space as free. A data recovery utility can search the entire drive, rebuild the FAT and bring back what you think may have gotten ridden.

Smashing the drive is a good idea, if you don't have to return it that is. You might have some explaining to do otherwise:

Them: "We have noticed some damage to the drive you returned to us".
You: "Oh it must have got damaged in the post, or I dropped it".
Them: "I don't think so, warranty is void".

Trying to think of the wipe utility my sysadmin friend used - but there are plenty out there.

[#6]

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@Alex wrote:

just deleting files doesn't actually delete them. It just updates the drive FAT (file allocation table) to think it is and marks the space as free. A data recovery utility can search the entire drive, rebuild the FAT and bring back what you think may have gotten ridden.

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File shredders do just that though. They'll replace the file contents with random data (as i mentioned above) save the file and then rename it to something random before deleting it. From that point on the OS is doing exactly the same operations as it would for any other file.

Many of these programs talk about disk passes etc however that is controlled by the operating system. To get around that all the programmer can really do is to save to the existing file overwriting the entire content in the process. If you do that enough times using your own random data generator and save it each time, that is technically data erasure and counts as a pass as it's a write operation. Tell the OS to rename it to a random name and then delete it and that's it - your original content is gone for good.

[#7]

Yep I know @7up how I wish life were that simple.

Working for a financial company we had silly laws, like anything with personal data had to be called a certain file name. So we 'knew' (massive inverted commas) where it was located.

I gave up trying to explain that Office (the Microsoft version that is) saves cached data in temporary locations on the drive. For anyone who doesn't believe me who has Windows right now, try a Cmd-R, type %TMP% and press enter?

[#8]

I've used https://dban.org/ in the past to wipe drives. You can use it from a bootable USB stick, just be careful you select the correct one if you have multiple drives !

[#9 · Accepted solution]

Thanks very much for all the suggestions.  Sadly, none can help any more because all I now get is "Device error" whenever I try to access the disk.  The vendor has had the cheek to offer me a mere £7 as compensation but told me to keep the drive.  As this is an ebay purchase, I suspect that represents his profit and that the disk was despatched from a third party, central (Chinese) supplier.  The answers he has given asking me to do this and that all suggest that this is a common experience.  All I can say is to take great care when buying from ebay.

The sad thing is that, purely aesthetically, it is a very nice looking piece of hardware.  Shame it does not work !

I am really grateful for all the suggestions and insight.  I am now looking on ebay for a good deal on hammers !

Thanks again.

[#10]

I missed this topic earlier, but the only way to reliably wipe a disc is to use a suitable utility; editing files almost always writes the new file to a different location, leaving the original intact.

For future reference, download the UBCD ISO (search for UBCD) and use one of the "disc wiping" utilities which will write various data patterns sector by sector ignoring the disc partitioning layout.

[#11]

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@WinfredVaughan wrote:

...  The vendor has had the cheek to offer me a mere £7 as compensation but told me to keep the drive.  As this is an ebay purchase, I suspect that represents his profit and that the disk was despatched from a third party, central (Chinese) supplier.  The answers he has given asking me to do this and that all suggest that this is a common experience.  All I can say is to take great care when buying from ebay.

.

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@WinfredVaughan 

I don't think you've mentioned how long ago you bought the disk, but if it's a recent purchase there's a possibility you could raise a complaint to eBay, which, as you've already tried to reason with the seller, could well result in a full refund with no requirement to return the dodgy goods.

[#12]

I'll ask my sysadmin friends about good utilities, they'll know.

Can't remember the name of the one they used to use - hmm actually I think I can now so feel free to PM me (before the PC Brigade here tell me off for advertising so I won't post it on here). 🙄

[#13]

@WinfredVaughan 

I've just sent you a PM on what I've been recommended, hope it helps.

[#14]

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@Alex wrote:

I'll ask my sysadmin friends about good utilities, they'll know.

Can't remember the name of the one they used to use - hmm actually I think I can now so feel free to PM me (before the PC Brigade here tell me off for advertising so I won't post it on here). 🙄

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I think you're a bit late to the party mate - i've already suggested eraser and the op has already replied saying the disk is now dead.

Why are you only now contacting your sys admin friend? - Horse, door, bolted..

[#15]

Sorry for trying to help, as you can probably tell dealing with a dead drive is not something I've ever really dealt with before.