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  1. #21

    Thumbs up

    Thanks oz. Looking at that wiki now... appreciate it.
    Out of curiousity. I have a couple of Windows based o/s' and Partition magic so I guess it's fair to assume this applications 'format' option would wipe the drive, I'm just not sure to what extent (ie. ant recoverable data) so any advice on whether that's feasible would be appreciated.


    Oh and one other similar question:
    I have rm -rf several directories, is there a command which will show me (much like I dunno, deleted items in Outlook for instance) whether there is data I've deleted, that is still... available??

    Thx again!

  2. #22
    Join Date
    May 2004
    arch linux
    Simply formatting a drive doesn't fully remove the data from the drive. That's why options like secure erase, shred, dban, and others exist.

    As for finding data that you've deleted, you can often retrieve files and data using TestDisk and/or PhotoRec, both of which are also included on the earlier recommended Parted Magic LiveCD. Instructions for using them can be found on the TestDisk website:

    TestDisk - CGSecurity

  3. #23
    Thanks for your time oz... I'll give your advice a go!

  4. $spacer_open
  5. #24
    Trusted Penguin Irithori's Avatar
    Join Date
    May 2009
    or you can build your own secure erase.

    from any liveCD, including knoppix, you could do that as root:
    dd if=/dev/urandom of=/dev/sdc bs=1M
    Be *very, very* sure, that sdc is the disc you want to erase.
    dd will start overwriting with random data without further warning.

    That may take a while.
    As before, you can judge the speed with
    vmstat 1
    I would expect, that the dd will break with an error at some point.
    Because the disc has an error and probably cannot be completely overwritten.

    You can also repeat that overwriting as often as you feel neccessary.
    Ranging from:
    1 - should be good enough
    up to
    7 - batsh*t paranoid

    A faster method would be
    dd if=/dev/zero of=/dev/sdc bs=1M
    Zeros are easier to generate than (fake) random numbers.
    This should actually saturate your usb bus, ie: around 30MByte/s.

    or you just abuse badblocks.
    badblocks is a tool to search for... bad blocks.
    With the following parameters, it will overwrite the disc 4 times:
    with 0xaa, 0x55, 0xff, 0x00 as patterns.
    As root:
    badblocks -svv /dev/sdc
    Last edited by Irithori; 08-17-2010 at 02:54 AM.
    You must always face the curtain with a bow.

  6. #25

    Thumbs up

    Just wanted to update my fellow Linux folk just for the benefit of anyone reading this if they needed the same advice. In the end I used the shred command with a switch to change the number of 'passes' (chose 7 in the end) and my WD NAS is now back with WD with all my data off and nice and clean...!

    Irithori, thanks for all your invaluable help...!

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