File Obliteration
There are two options provided to obliterate data to prevent subsequent recovery or access by unauthorized individuals. The data are obliterated by overwriting the entire allocated space of the file, not just the used space. In addition, the OS/2 cache feature is bypassed for these writes to ensure that the data is actually written to the disk on each pass.
Since the cache is bypassed and the obliteration requires multiple reads of the entire files allocated space, performance is slower than other functions such as deleting files.
Any EAs will be erased when the file is obliterated but the EAs are not obliterated.
Option 1
Fast Obliterate - This option is for users that want a faster obliteration and don't require Department of Defense level obliteration. It overwrites the entire allocated file space in three passes and then verifies the last write in a fourth pass;
Pass 1 - Overwrites with 0
Pass 2 - Overwrites with 1
Pass 3 - Overwrites with a random but constant character
Pass 4 - Verifies the random character
Option 2
Obliterate - This option is used when a Department of Defense specification level of obliteration is desired. It overwrites the entire allocated file space in seven passes and then verifies the last write in an eight pass;
Pass 1 - Overwrites with 0 Pass 2 - Overwrites with 1
Pass 3 - Overwrites with 0
Pass 4 - Overwrites with 1
Pass 5 - Overwrites with 0
Pass 6 - Overwrites with 1
Pass 7 - Overwrites with a random but constant character
Pass 8 - Verifies the random character
Obliterating Files
Select the files to obliterate in one of the two file windows.
Files from multiple directories may be obliterated in one step by reading the desired directories into the same file window before starting obliteration of the selected files.
To read a directory and all its subdirectories into a file window, either select the Read Branch menu item from the Directories menu or double click the directory while holding down the SHIFT and CTRL keys.
To add a single directory to the file window, either select Add Dir from the Directories menu or double click the directory while holding down just the Ctrl key.
You may add as many directories as desired by repeating the above steps.
You may read the entire drive into a file window for obliteration by double clicking the root directory while holding down the Shift and Ctrl keys.
Only selected files are obliterated. You may push the Selected button in the Data Panel or use Ctrl+/ to select all files. By default, FS/2 uses extended selection of files so that a single click in the window deselects all files. This eliminates the possibility that a user may not notice selected files outside the view space of the window and perform an unintentional action on a file.
Another necessity for obliterating all files in directories is to ensure that no file filter is set when the directory is read. Look at the File Filter dialog to ensure that all files are to be included. In addition the '*' (read all) file mask, make sure that the 'R S H A N' radio buttons are all set to '+' (include) to include files with any or no attributes set.
Once all files to obliterate are selected in a file window, simply popup or pull down the Files menu and select Delete->Fast Obliterate for the faster of the two obliterate options or Delete->Obliterate for obliteration that meets DOD level obliteration. A confirmation dialog always appears before obliteration starts. Press Ok to start obliteration or 'Cancel' on the dialog to abort the operation.
Obliteration may be stopped and/or aborted while in process by pushing the large button at the bottom of the window labeled 'Push or ESC to abort'. Files that have been processed are indeed not recoverable however.
Read only files are deleted without asking the user. Other errors will cause the Obliterate Error dialog to appear. A typical cause may be a sharing violation. If a sharing violation is encountered, close the application that has the file open and then hit the Retry button. Use the Skip button to skip any file for which an error has occurred.