What is the difference between Deleting and Formatting

[abhinavsingh310]

I need details about the hardware changes, how are these methods of deleting the data different?
A shift delete will also delete the data and formatting will also poof the data, so how these memory is effected in both of these mechanism?

Please HELP!!

 

[Acidicheartburn]

If I remember correctly, deleting a file in windows normally involves deletion of the index information for where the data is located on the storage drive. Essentially, because the location of where that data was stored is lost, and now the drive doesn't know what's there, the space is marked as "open" for use, or in more layman's terms, it becomes empty. This is why deleted files can be recovered in windows systems. The data isn't actually erased, its location has just been forgotten. Special programs and know-how can allow you to find that information again and bring it back.

There are two types of formatting, at least under windows. There is the quick format, which just deletes the entire drive index information. Again, all of the data is still there, it's just seen as empty to the OS and can be rewritten at will. Normally a quick format is all you need to "erase" a hard drive and make it empty. This is how you reformat and reinstall Windows when you use the Windows install utility.

Then there is the full format. The full format actually truly erases everything on the drive by writing every bit in a 0. This information is generally unrecoverable. Full formatting takes a long time (upwards of an hour and more depending on the size of the drive) on hard drives, versus a quick format which only takes a few moments to perform.

Someone correct me on anything I may have gotten wrong.

 

[Harvey]

Someone correct me on anything I may have gotten wrong.

You got it right as far as you went. However, data recovery services can often recover at least some data from a formatted drive by reading the actual bits on a disk.

If you need to protect against that, there is software that will do a secure wipe by writing all zeros to the entire recordable surface of the drive. A truly secure wipe would repeat the process several times to make sure there were no discernable residual magnetic patterns within the overwritten areas.

More info from PC World.

 

[Acidicheartburn]

Indeed. That is why supposedly the NSA uses a 7 pass secure wipe on their HDDs. I left that part out because I didn't think he needed that kind of details. That link you posted is actually helpful to me, I'm about to attempt a secure wipe in a few hours to fix a slow login problem plaguing my SSD. Cheers!

 

[Harvey]

That link you posted is actually helpful to me, I'm about to attempt a secure wipe in a few hours to fix a slow login problem plaguing my SSD. Cheers!

Amazing what you can learn on friendly forums. Cheers back at ya.

 

[Berryracer]

Indeed. That is why supposedly the NSA uses a 7 pass secure wipe on their HDDs. I left that part out because I didn't think he needed that kind of details. That link you posted is actually helpful to me, I'm about to attempt a secure wipe in a few hours to fix a slow login problem plaguing my SSD. Cheers!

that's a VERY bad Idea.

You see, secure erasing a drive has many methods.

If you write all 0s or all 1s to the SSD, that leaves the SSD in a state where all the cells are in a written state which then it has to recover and make it writeable again so that will actually slow your performance even more.

The special tools such as the one in Parted Magic which you can only delete all partition and file system info is what you need to do. That's why a secure erase of a Samsung SSD for example using the Samsung Magician takes no longer than a few seconds. It doesn't write 0s or 1s to the entire SSD. you don't wanna do that!

Read this thread to know more about which secure erase to do for an SSD:

Which one of these options to choose for SECURE ERASE?

 

[Acidicheartburn]

that's a VERY bad Idea.

You see, secure erasing a drive has many methods.

If you write all 0s or all 1s to the SSD, that leaves the SSD in a state where all the cells are in a written state which then it has to recover and make it writeable again so that will actually slow your performance even more.

The special tools such as the one in Parted Magic which you can only delete all partition and file system info is what you need to do. That's why a secure erase of a Samsung SSD for example using the Samsung Magician takes no longer than a few seconds. It doesn't write 0s or 1s to the entire SSD. you don't wanna do that!

Read this thread to know more about which secure erase to do for an SSD:

Which one of these options to choose for SECURE ERASE?

I was just going to plug the SSD into another computer and use the Secure Erase function in OCZ Toolbox.

 

[MongGrel]

Write 0's to disk might cover a lot of things, I'm not worried about it most the time and have only done it once on a failing drive to see if it was reporting right.

I am probably wrong of course.

It wasn't a SSD though, I doubt that would be a good idea.

 

[abhinavsingh310]

That really really helped!!

However Acidicheartburn!! Can you tell me little more that 7 Pass secure wipe which is being used by NSA?

That sounds really interesting!!

 

[Acidicheartburn]

Supposedly the NSA runs 7 passes of a full format across their hard drives to make sure all of the data is erased.

 

[John Connor]

The NSA only uses degaussing or destroys the HDD.

http://thestarman.pcministry.com/asm/5220/

http://en.wikipedia.org/wiki/Data_erasure

Personally I would get a degausser or use thermite to destroy the drive. The chemicals for making thermite are on eBay. I do have DBAN though.

 

[John Connor]

There is a program called low level format tool that could be used. I had a drive acting up and I used this and it made the drive better, but not 100%. Keep in mind only the manufacture can do a real low level format.

http://download.cnet.com/HDD-Low-Level-Format-Tool/3000-2094_4-75544788.html

I don't think a slow format writes 0's. I think all it does is mark sections if they are found bad, i.e checks the drive for errors. I have succesufuly recovered a drive after a format.

For SSDs you can use Parted Magic. http://www.cnet.com/how-to/how-to-securely-erase-an-ssd-drive/

 

[mv2devnull]

Partitioning is like taking a blank paper.

Formatting is like printing a grid with row and column labels (a calendar) on that paper. Initialization of filesystem metadata. Does not require that data blocks are touched

File creation is like writing an event for some day.

Deletion is like scratching that event. An update of filesystem metadata. Does not require that data blocks (of the file) are touched.


It is up to the filesystem, which blocks are rewritten during each operation. Filesystems are many.

It is entirely possible to write to a block device that does not have any filesystem data or even any partition table. I resume that DBAN (and some databases) operate on this level. Raw writes.