Erasing Harddrive.
So I burned Trisquel ISO to a disk using InfraRecord on Windows 8.1 and then I am using that to install Trisquel. But I cannot securely erase my whole HDD using Trsiquel, for some reason fedora's tool for drive erasing just works, I am currently doing so with the "ATA Enhanced Erase" option as compared to the "overwrite with zeroes option".
Which option for erasing should I be using?
I've got no idea what "ATA Enhanced Erase" is, but if I'm not mistaken, I know of 2 ways of deleting a drive's contents.
One is the overwriting with zeroes thing. It takes a long time, but basically removes all data.
The other method I know of (which I think is more commonly used) is that it simply makes a computer think there's blank space where there isn't which, if that "blank" space is used, it will only take place by the data that was already present being overwritten (with no dramas whatsoever). The data that's not yet overwritten can still be recovered using file recovery software.
http://www.dedoimedo.com/computers/low-level-formatting.html
"But I cannot securely erase my whole HDD using Trsiquel"
I assume you mean from the live session. If so, does installing GParted and erasing using that help?
Yes from the live session.
"One is the overwriting with zeroes thing. It takes a long time, but basically removes all data." ~ Does GParted have that option? To overwite with zeroes?
What's wrong with just using shred? It overwrites the entire drive with random
data, effectively wiping it.
On the other hand, if you want that feeling of cleanness, then dd if=/dev/zero
of=/dev/ does the trick.
These two are by far the simplest and most effective solutions to my knowledge.
That's sounds great.
So shred will write random data to the disc and overwrite all old data (prventing recovery of that data) until the disc is full. :D
I did some reading on the subject of secure erase and found very little except a great example of stupid things PhDs [1] say [2]. Italics by yours truly. Just wanted to share these gems with you. (Why yes, I'm a cranky old bastard.)
"It should be noted though that a secure erased drive that is then physically destroyed would be extremely difficult if not impossible to recover data from."
"Investigations at CMRR at UCSD have shown that a single pass secure erase at lower frequencies results in no remaining data signals and a second erase reduces this signal only slightly more."
1 http://cmrr.ucsd.edu/people/Hughes/
2 http://cmrr.ucsd.edu/people/Hughes/documents/QandAforwebsite10212008_000.doc
So that above link explains ATA Enhcaned Erasing.
So which one is better?
I am running an ATA Enhanced Erase now, but I do not mind running the normal "overwrite with zeroes" option.
Aparently ATA Enhanced Erase is something built into the BIOS. ~ http://www.zdnet.com/article/how-to-really-erase-a-hard-drive/
I'm no expert so I can't fully understand the ATA Secure erase page (it seems to also make data irrecoverable by recovery programmes if done to an SSD).
The thing is though, if you let the current erasing process finish and end up with an empty drive after that, you (should) be able to install Trisquel on it regardless as to whether there's any data there un-overwritten.
P.S. Overwriting with zeroes seems to be most important for "Low level formatting is a hard disk operation that should make recovering data from your storage devices impossible once the operation is complete. It sounds like something you might want to do if giving away a hard disk or perhaps discarding an old computer that may have contained useful and important, private information."
I know, I just like a clean drive. :D
DBAN (Darik's Boot and Nuke) is useful for overwrite all data on the disk: http://www.dban.org/ However it is not suitable for SSD disks. Other method is boot using a Trisquel Live session and then use shred utility from GNU coreutils via a command line. https://www.gnu.org/software/coreutils/manual/html_node/shred-invocation.html
So like...:
shred /dev/sda
'shred' is the best solution. It writes random data instead of zeros. By only writing zeros (as in 'dd if=/dev/zero of=/dev/sda'), expensive equipments can still recover some data (because writing a zero on top of a zero leads to a "magnetic state" that is closer to zero than writing zero on top of a one).
Okay. Thank you. :) I will definitely be using this for fully wiping all my HDD's.
> 'shred' is the best solution. It writes random data instead of zeros. By only writing zeros (as in 'dd if=/dev/zero of=/dev/sda'), expensive equipments
> can still recover some data (because writing a zero on top of a zero leads to a "magnetic state" that is closer to zero than writing zero on top of a one).
but you can writes random data instead of zeros useing dd
dd if=/dev/random of=/dev/sda
dd if=/dev/random of=/dev/sda
That would take ages. You probably meant 'dd if=/dev/urandom of=/dev/sda'. One more character before "random" that makes much difference on the running time! That latter command is indeed analog to 'shred -n 1 /dev/sda'.
sudo shred -v /dev/sdX
Two questions:
Is shred shipped with trisquel and also what is the "-v" argument for?
-v, --verbose
show progress
Oh okay, thank you.
That command-line argument is damn helpful for that binary; shred.
As compared to using the Disk Utility in Live Session mode for Trisquel, will the shred utility work while Trisquel is runnign off of an optical disc?
Thanks in advance.
Thanks everyone. For all of your helpful replies :D
There are also two command-line utilities for erasing disks in a default Trisquel repo. These are wipe and nwipe.
-z with shred will overwrite with zeros on the final pass if you really want to. But its not nescessary especially if you are going to use the disk again for reinstall.
-n tells it how many passes to do. (default is 3 passes)
so shred -n 2 -z -v /dev/sda will probably take like 5 hours on a 1tb.
But i would recommend just doing shred -v /dev/sda, think it took maybe 30 mins to an hour with my 1tb 7200 sata, and is also probably unescessary...lol
dban uses the DoD method, and is probably extreme overkill. The 7 pass setting is good for when you are throwing out a drive.
I will do a three pass wipe with shred then. :D
I am shredding my HDD now. Thanks guys. That was so easy. :D
Our pleasure.