deleting data

[newbee]

What happens to the data once I delete a file or application? The data was stored in machine language on my system then I delete it and then empty my recycle bin. But how is that space cleared up and where does the data go? How is it being removed?

[Rick]

It is NOT remove.
The disk space is simply marked as available.
It will remain on the drive/disk till it is over written by another file.

Text.txt file when deleted is renamed to $ext.txt

The Disk operating system reads that entry in the (Fat) File Allocation table as available .
If and when it does a disk write it will over write that area of the disk

This is also why Undelete is able to recover deleted files.
If fines these Files and simple renames again to a normal dos file name
if the file or parts fo the file have not been over written

[This message has been edited by Rick (edited 02-14-2002).]

[Paul Komski]

Put very simply. The machine code is stored at an "address" on your disk, etc. (In old Basic; the bytes are POKED into numeric locations). Moving the file to another folder (including the recyle bin) involves some readdressing. After that it sits there until it is overwritten.

PS Sorry Rick yours is much more comprehensive. I got called away and didn't submit in time!

[This message has been edited by Paul Komski (edited 02-14-2002).]

[Vic 970]

If you want your files to be irrecoverable by undelete, you can use a prog to overwrite (the file) at the same time as you delete it.
Or you can overwrite all your empty (available) space with 'junk' data (with same prog)

You also get an option of how many times to overwrite to prevent recovery.

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for every question there's an answer. Then a load more questions.
Definition of Upgrade "A means of introducing new bugs to a program to replace the ones that you have eventually found fixes for"

Regards..,
Vic.

[Beno]

In a simple analogy consider this.

When you go to the library, you usually look for your book by going to a catalogue where all the references to books are kept. This is like the FAT.

When you find the reference to the book, you can then go to Level 2 section 12, or whatever,to get the specific book. This is like going to the hard-drive.

When something is deleted in a computer it is like you going to the library catalogue and throwing out the card reference to say........."Harry Potter" book. The book is still there..........however no-one who walks into the library knows because there is no card reference to it. Do you get it?!!

Programs like Norton Disk Utilities are able to find lost data given a search string as a reference, because unless the location where the data was once stored has been written over, it can be recovered - pretty cool huh!

Hope that helps

Beno

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"Don't stop till you get enough"

[newbee]

Thank you everyone, that helped alot.

[iisbob]

Excellant explanantion Beno! http://www.PCGuide.com/ubb/biggrin.gif

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iisbob

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