I'm trying to back up some older PC game discs and I'm confused about the difference between using the dd command and simply dragging the disc's contents into a folder. dd seems to fail fairly often, while copying the files appears much more reliable. If I copy all the visible files, will I still be able to install and use the game, or do I need to create a complete image with dd?
3 Answers
Drag-and-drop copies the files that the filesystem exposes. That can be enough for a game installer if the disc only contains ordinary files, but it may not preserve boot information, hidden data, multiple sessions, or other disc-specific details. dd copies the entire disc sector by sector, including the filesystem, layout, and unused or hidden areas, so it creates a much more exact image. For an optical disc, saving an ISO is usually the convenient way to make that image.
The two operations do different jobs: drag-and-drop is a file-level copy, while dd is a raw byte-for-byte copy from one device or image to another. That’s why dd can reproduce the whole disc, but also why using it incorrectly can overwrite the wrong drive. Double-check the input and output devices before running it.
If you mean an optical game disc, copying its files can work when you only need the installer. It may fail if the game expects the original disc structure or uses copy protection, though. A disc image is the better choice for archival purposes. Also, dd does not understand filesystems and stops or reports errors when it encounters a read problem; for a scratched or failing disc, a recovery tool such as ddrescue is generally more suitable.
So copying the visible contents might work for installing the game, but it wouldn’t necessarily be a complete backup of the original disc?