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How can I quickly wipe a disk (filesystem/partitions) without overwriting all content with random data? For example shred could accomplish what I want but takes to much time.

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    1. Do you want to overwrite everything with zeros which is faster than with random data? 2. Do you want to change the mapping (which is faster than overwriting with zeros (and at least as secure)? 3. Do you want to destroy the drive physically? 4. Do you want to 'only' wipe the partition table (or better the first mibibyte) and replace it with another partition table with one or more partitions with new file systems without overwriting all data? This can be very quick, and will work well, if you intend to use the drive yourself. – sudodus Jul 2 '18 at 20:31
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    What is the goal here? Security? – Duncan X Simpson Jul 2 '18 at 21:39
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If you don't care about actually destroying the data on the disk, you can probably do something like dd if=/dev/urandom of=/dev/sdc bs=1M count=2 to fry the first couple of megabytes (which would include the MBR and partition table).

Be super-duper sure about which block device you point at as there are no taksey-backsies on this command

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    Be aware that this is very insecure. Although the partition table is deleted, the file-system is left completely intact. Nowadays, tools align partitions to 1 MiB boundaries by default. An average user would plug in the drive, create a new partition table and a new partition. The file-system would be discovered with all data instantly available. It does not even need an IT professional for this to happen. The situation is even worse in case the disk contains a GPT. The operating system would find the undamaged secondary header and would simply recover the partition table. – Hermann Aug 31 '18 at 11:03
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    The OP asked for quick, not secure. – DopeGhoti Aug 31 '18 at 15:08
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    True, yet this method is so far on the "fast" side of "fast vs. secure" that data can be recovered by accident. I recommend overwriting with count=2 so the header of the first partition is destroyed as well. Not much slower, but it yields a dramatic increase in security. – Hermann Aug 31 '18 at 17:46
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    Fair. I've adjusted the count. – DopeGhoti Aug 31 '18 at 17:47
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The fastest (and also the safest) is to encrypt the whole disk when it is new. Then, to erase, just erase the encryption key. Done in half a second, unfeasible to recover any data.

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    Very true. But not so useful after the fact, though. – roaima Jul 2 '18 at 21:17
  • Which fact????? – Jamie Hutber May 14 '19 at 21:38
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    @JamieHutber The "after the fact" is an English idiom to express "after something has been done already". In this case, after the disk has been used it becomes more difficult to make a "whole disk encryption". Still doable IMO. – Isaac May 14 '19 at 23:08
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A really quick and easy option for magnetic disks is a degaussing bulk eraser. 20 seconds and your data is gone forever.

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ATA Secure Erase is available on non-SSD drives, too. See https://askubuntu.com/questions/42266/what-is-the-recommended-way-to-empty-a-ssd on how to request the operation.

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  • To clarify: ATA Secure Erase is a procedure which allows you to ask the disk drive to completely erase itself, and once the erasure process has been started, the drive is supposed to not accept any other commands until it has been completely wiped. If properly implemented in the disk firmware, even removing the power mid-erase should not help: the disk should go right back on erasing itself as soon as the power is re-applied. For threats advanced enough to interrupt this, you'd need some form of physical destruction anyway. – telcoM Aug 31 '18 at 19:14
  • @telcoM it seems trivial to get an identical disk that isn't erasing and swap the platters which contain the actual data. – AnnoyinC 2 days ago

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