Why it's important to always process system disk even if you just wipe data on external oneIMPORTANT RULE:
Always run a wiping procedure on the system disk also! See below why this is important.
Description of an issue
While working, Windows OS copies some files (usually images) to a temporary folder. This is done to increase the performance of your external storage or to provide backup functionality during editing. Windows OS will later delete those cached images or files from the temporary folder.
But the problem is that the temporary folder is located on the system disk (usually C:), even if the original file is located on another (external) disk, for example, F:
Thus, in some situations, files can exist in two different locations; though they can't be recovered from the original place, they can be from the system's temporary folder as these are physically different places. You may not know that the file being accessed had a duplicate in the temporary folder for a while.
That's why it's very important to run wipe procedures on the system disk as well, even if the original file was located on another external one. In such an instance, even if the viewed file was cached to the temporary folder by the OS and was later deleted, it will be also securely wiped to prevent restore.
★ User manual (all help topics)
★ Why quick mode is not available for all disks?
★ Why it's important to always process system disk even if you just wipe data on external one
★ Explanation of security options
★ Why I don't see some disks in the list for processing?