Data Destroyer
Section 10: Purging a disk

Purging (a.k.a. cleaning or wiping) a disk consists of purging the free space plus purging all files in all folders, except optionally for the top-level files and optionally files in selected top-level folders. (Top-level files and top-level folders are those in the root directory, e.g., C:\.) It can be used to wipe hard drives, writeable data CDs and pen drives (a.k.a. memory sticks).

The program does not implement a limit on the size of a hard drive, but there are a couple of practical limitations. Firstly, overwriting files multiple times (required for secure file deletion) takes time, and the larger the hard drive the more time is needed, so that, say, a 100 GB hard disk might require more than 24 hours to wipe. Even with a fast PC which can write very quickly to the hard disk, a very large hard drive may require several days of continuous overwriting. Secondly, older PCs may have hard disks which are slow to write to (compared to recently manufactured hard disks), so even a 40 GB hard disk may take a long time to wipe. For this reason Data Destroyer implements a disk write speed test, so that you can get an estimate of how long it will take to wipe a hard disk. The estimate is only rough, but it will give you some idea of the time needed. If the time seems too long then reducing the number of overwrites (by changing the type of purge) may reduce the time required to an acceptable amount.

If the time required to wipe an entire hard drive is unacceptably long then an alternative is to just wipe selected folders. This, however, may still leave sensitive data lying around in free sectors on the disk, though they cannot be read by using ordinary software such as Word and Excel. The free space itself may or may not take a long time to wipe, depending on how much of it there is (a disk which is nearly full will, of course, have little free space).

If you are running Windows XP and the disk to be purged has a folder called 'System Volume Information' (it may be hidden) then it is recommended to turn off 'System Restore' for that disk (do this via My Computer | Properties | System Restore). This will cause all files in that folder to be deleted. (For information about this folder see here.)

Clicking on the Purge disk button in Data Destroyer leads you through a process which is illustrated by the following screenshots:

If the purge speed for the selected disk drive has not been tested then the following appears:

When the purge speed has been ascertained the purge time is estimated:

As noted at Testing purge speed, the estimate of the time required to purge the disk is not precise. The actual time could be significantly smaller or larger.

A Yes leads to the folder selection window:

This means: purge all files in all top-level folders on Drive D (and in all their subfolders) except for the files in the folder Program files.

If a folder is shown as "Permission denied" then it should be excluded from the purge (this is the default setting).

After clicking on the Accept button you are asked:

Answer Yes only if you wish to leave the program running unattended (say, overnight) during a long purge operation.

After writing the dummy file the program proceeds to purge it (and thus the free space).

Next: Saving and Loading the setup
Data Destroyer Main Page Hermetic Systems Home Page