Legacy software hosted on third-party "warez" sites or generic file-hosting services is often corrupted. You might download a 500MB ISO file only to find it is incomplete or contains unrelated filler data. When you try to boot from it, you will be met with errors, wasting valuable time during a crisis.
Often called the "Swiss Army Knife" of imaging. Clonezilla: Powerful, though it has a steep learning curve. acronis true image 2016 iso download free