I have 1TB drive, I need to completley erase/overwrite all data.
What would be the quickest way under linux?

thanks.

dd if=/dev/zero of=/dev/sdx count=1025000 bs=1025000

Substitute the correct device for /dev/sdx

jlinkels

1 members found this post helpful.

That would be a very, very good idea

BTW, AFAIK there's no need for the count=<whatever>. Without it, dd will keep going until it gets to the end -- which avoids the danger of not calculating it correctly.

What will be the default count and block size if one does:

bs=512
count is indefinite

jlinkels

1 members found this post helpful.

I think dd usually defaults to a block size of 512 (easy to check)

As already stated, the default count is "forever"--ie it keeps going until there's nothing left to do.

With dd, you can find the "quickest" way by experimenting with the block size but---regardless--- wiping a 1TB drive is going to take a while.

Do a timed test with a low value of count, and you can extrapolate to know just how long. (I'm guessing dinner + a good night's sleep)

Not at all. If this is a reasonable modern system, the speed should be limited by the transfer rate of the disk. The specified transfer rate of a 1 TB disk is about 3 GB/s. Let's be pessimistic and assume 1 GB/s. Then it would be done in 20 minutes or so.

jlinkels

1TB = ~10E12 Bytes @ 59E6 Bytes/sec = ~ 4 hours

I'd run something like:

You can try different 'bs' options, because performance can vary based upon the value. I don't specify a 'count' if you want to wipe every last bit.

1 members found this post helpful.

Same here:

Didn't know it was that bad.

jlinkels

Returning to the original question and given the demonstrations of how slow dd is, I wonder if there is some OEM-specific way of telling the HDD firmware to do the job, perhaps a destructive low level format?

I always smile when the 'how to clear a drive' question comes up. The various recipes for DD, the hours of work, DBAN and our local council even link to this: http://www.killdisk.com/downloadfree.htm when telling people how to clear old hard discs. All this is fine and dandy but....

http://cmrr.ucsd.edu/people/Hughes/SecureErase.shtml
...probably the quickest way to do it is with Gordon Hughes 'Secure Erase' which is built in to most post 2001 HDD drives. It takes about 2 1/2 hours to per 500gb - fraction of the time of other methods.

To run it requires a bootable floppy/cd/usb as it's a dos.exe file that talks to the ATA controller on the motherboard and sends the drive the correct ATA commands to securely erase it.

As drives get bigger the time taken to use other tools rises exponentially so I hope that helps someone out.

On a side note I was recently read that wiping drives with patterns more than 1 time is really a waste of time. A single wipe of any pattern will render any data beyond recovery for your average Joe. Even a forensics lab using an atomic force microscope to view the platters would take three months to recover a 36k jpeg file that has been single wiped with any pattern.

Adding to that, Scott gives some great 'talks' on drives. Normally I'm not a fan of Youtube videos but this series is rather good. It's well shot, to the point and without the usually waffle:

http://www.youtube.com/user/SuperFly.../0/fst8IZup44c

I didn't know they could recover it at all. Any links ? Cuz I would like to see some undeniable proof for this urban myth, that if you wipe once with zeros, the gubmint using uber technology, can still reliably recover something.