Comments on: Using dd to blank a drive

By: Thinking things through: dd over USB1.1 « Motho ke motho ka botho

Thinking things through: dd over USB1.1 « Motho ke motho ka botho — Mon, 23 Aug 2010 21:25:51 +0000

[...] quite ) to clone systems, backup entire drives, get visual snapshots of the data on a disk or to scramble the contents of a floppy or USB [...]

By: anonymous coward

anonymous coward — Mon, 08 Feb 2010 02:32:22 +0000

Several passes with /dev/urandom (while syncing in between passes) is by far one of the best methods you can use to destroy data. Even if you’re worried about forensic recovery.

Whenever I need to destroy a partition, I use:

for i in {1..5}; do dd if=/dev/urandom of=/dev/sdXX bs=1M && sync; done

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Sun, 07 Feb 2010 00:45:13 +0000

[...] Using dd to blank a drive [...]

By: Luca

Luca — Sat, 06 Feb 2010 09:56:06 +0000

That sounds like a better way, as it’ll also check the integrity of the device. Depending on how un-random it is, it should also not take much longer.

By: anonymous coward

anonymous coward — Sat, 06 Feb 2010 04:41:00 +0000

you certainly must have meant /dev/zero, right?

but yeah, and it’s even faster than /dev/urandom, naturally…

By: anonymous coward

anonymous coward — Sat, 06 Feb 2010 04:25:03 +0000

d’oh! here’s what the man page says about the ‘-w’ option:

With this option, badblocks scans for bad blocks by writing some patterns (0xaa, 0×55, 0xff, 0×00) on every block of the device, reading every block and comparing the contents.

By: anonymous coward

anonymous coward — Sat, 06 Feb 2010 04:18:54 +0000

and then there’s always the ‘badblocks’ command which comes with the ‘e2fsprogs’ package which allows you to check for … well, bad blocks on a device. I used to use the -w option almost all the time…

By: Mehall

Mehall — Sat, 06 Feb 2010 01:09:28 +0000

I hate to say wrong to you, but dd is actually by far one of the best ways to blank a drive. However much faith you put into DBaN, dd does the job so well, that if it completes a run (even if using /dev/null instead of /dev/urandom like you suggested) that many professional forensics recovery companies will refuse to try, as it is a waste of their time and your money.

dd is a fantastic tool. Whenever I get a machine that I may have to return to the original owner, or to someone else significantly clueless about computers, I make a disk image to my external HDD, then wipe the disk (all using a live CD) using dd for both operations. a quick run of gParted later, and the disk is ready to have a new OS installed, but if I need to return it to the condition I got it in, dd will do exactly that given the disk image instead of /dev/null