Frequently Asked Questions (FAQ)

This FAQ applies to v5.3 of Eraser, and is no longer updated.

If you cannot find an answer to your question here or by reading the help file, you can always try studying the source code.

Available topics are Basic Information, Security, Using Eraser, Downloading, and Bug Reports and Suggestions.

Basic Information

Q: "Which operating systems does Eraser support?"

A: Windows 95, 98, ME, NT 4.0, and 2000 (all versions, with or without service packs). Eraser v5.3 has not been tested on other platforms.

Q: "The antivirus software I am using reports that Eraser has a virus! What should I do?"

A: The Eraser distribution available at this site does not contain viruses. If you are worried that someone has modified the program, verify the digital signature. If the signature is valid, report the false alarm to the manufacturer of the antivirus program.


Q: "Overwriting is the key to ultimate security, isn't it?

A: Wrong. When overwriting data, you are simply trying to fix a security leak that already has happened, the best way to deal with this is to prevent the data from getting written to the disk in the first place - use strong encryption. E4M and GnuPG can get you started, but cannot help you with Windows-related security holes. If you must use Windows, use NT/2000. If you are serious about your security, try Linux, or even OpenBSD.

Q: "I have been using Eraser to overwrite all sensitive data from my drive. Is it really gone now?"

A: It depends on how much money and effort people trying to restore your data are willing to use. Erased data cannot be recovered with any software utility, and even if the hard drive electronics are bypassed and disk platters are examined, recovering data will be extremely difficult, if not impossible. You may want to read more about the common security problems from the help file though.

Q: "I heard that Eraser doesn't wipe the filename when overwriting the rest of the file? Is this true?"

A: No. You can choose whether filenames are cleared or not, and Eraser can even clear names of all previously deleted files (when erasing unused disk space).

Q: "I heard that Windows' swap (or paging) file may contain sensitive information. Why doesn't Eraser take care of this?"

A: When starting, Windows opens the swap (or paging) file with exclusive access, preventing any application from accessing it. This is quite understandable as messing with the virtual memory while Windows is running would probably crash the system.

Eraser, running on Windows, cannot access the swap file. The only way to overwrite the swap file contents (while keeping the virtual memory enabled in Windows) is to shutdown Windows, boot to DOS and use a DOS wipe utility, such as EraserD included with Eraser 5.0, to clear the file.

Alternatively, one can disable the virtual memory on Windows settings, reboot and overwrite the unused disk space on the drive where the swap file used to be. After completing the procedure, enable the virtual memory and reboot. Unlike Windows 9x, NT (and 2000) has a built-in security feature that causes the operating system to overwrite the paging file at shutdown; Eraser allows you to enable this feature.

Q: "But I know there are programs that wipe the swap file while Windows is running!"

A: There are applications that claim to overwrite swap file contents while Windows is running. They are usually trying to accomplish this by allocating huge amounts of memory and hoping that the operating system will write it to the disk (overwriting previous data). Doing this may even prove to decrease security instead of increasing it - instead of flushing the memory allocated by the overwriting program to the swap file, Windows may as well decide to save the memory allocated by some other application to the disk, possibly causing sensitive data that otherwise would have remained in the memory to end up on your drive. And even if the user is real lucky and everything goes as planned, the data currently allocated in the swap file still cannot (and will not) be accessed.

Using Eraser

Q: "Why does it take so long to erase a file? I know products that are much faster!"

A: Overwriting takes a while if it's done properly, especially on slower drives. If erasing with the other program is faster, it either uses fewer overwriting passes or it doesn't take care of flushing file buffers and data is never actually written to the disk. Either way, as a rule of thumb, faster erasing means worse security - instant erasing of even large files usually means no security at all.

However, if you find Eraser to be too slow for your taste, and you can live with lower security, use another overwriting method with fewer passes; that should speed things up.

Q: "When I erase unused disk space I get an error with a long list of files that could not be processed. What am I doing wrong?"

A: Nothing, the meaning of this error is to warn you that not all unused space on the drive could be overwritten. This is because the files on the list were loaded in memory and therefore, locked by the operating system and their cluster tips could not be erased. You can reduce the amount of locked files by closing as many applications as possible before erasing unused disk space. You can find more information about the cluster tips from the help file.

Q: "When I erase unused disk space I get a warning saying that the disk is full! Is this normal? What should I do?"

A: When erasing free disk space, Eraser fills your hard drive with temporary files and overwrites them. Therefore, for a short period of time, there will be no space left on your hard drive and Windows warns you about this. You don't have to run Disk Cleanup, and can safely ignore the warning message, because when Eraser is done, it will delete all temporary files it created.

Q: "When erasing data using the On-Demand eraser, all items on the list are removed after erasing and I have to enter the data again – is this how it is supposed to work? How can I set the tasks to stay on the list?"

A: Yes, this is the way the On-Demand eraser is supposed to work. However, you can set a task to stay on the list even after being erased by selecting the "Keep Task on List" option from the task properties window.

Q: "After running Eraser the free space on my drive was lost or reduced noticeably. How can I fix this?"

A: It could be that either Eraser was terminated abnormally or the system crashed causing the temporary files not to be removed. You can remove the folder "~ERAFSWD.TMP" and all the files in it to reclaim the disk space (open command prompt and type "deltree X:\~ERAFSWD.TMP", where X is the drive letter).

If your drive is compressed (with third-party compression software) and you did not turn off the cluster tip erasing, you must recompress the drive to restore the lost space – next time, do not use cluster tip erasing on compressed drives.


Q: "I downloaded an old version of Eraser from this site and afterwards noticed a later version was available. When I downloaded an update, it turned out to be the exactly same version I already had despite the different filename. What happened?"

A: If you try to download an older version of Eraser from this site, instead of delivering an old version, the server will send you the latest one. You can verify this by running the setup program, which tells you the version number before continuing with the installation. If you need an older version for some reason, you can download it from the archive.

Q: "Where can I get the source code for Eraser?"

A: Here.

Q: "Can I use Eraser source code in my own programs?"

A: The source code can be used, modified and redistributed under the terms of the GNU General Public License (included with the code). Basically, you may use Eraser source code in your own programs as long as you release your source under the same license. I would also appreciate a note if you use the code.

Bug Reports and Suggestions

Q: "I found a bug, how do I report it?"

Q: "I have a great new idea for the next version of Eraser, who do I tell?"

A: Visit the web site of the new maintainer for more information.