At NetApp in 2008 while we were struggling to define feature set of ONTAP 8, a product manager asked me if it was okay to ship backup in 8.0 and restore in 8.1. He quickly realized that this wasn’t going to work…
Unfortunately Apple has made a similar mistake with iCloud.
The problem with iCloud is that it is an image backup service. An image backup copies every disk block and restores every disk block. An alternative to an image backup is a file backup that restores every file. An image backup has the nice property that it is faster to restore than a file backup. The problem with an image backup is that it is a an all or nothing restore. If a part of the image has a corrupt file, then the backup is useless.
For example, if you have a firmware image in the iCloud backup that’s corrupt, then restoring the backup from iCloud restores the phone into a corrupted state.
And that is a problem. Turns out if you have let’s say 5 years of photos in those backups, there is no way to restore the pictures because the image contains the corrupt firmware.
This isn’t impossible to fix. Many backup apps that do image backup are also able to do file restores. Unfortunately Apple doesn’t offer that service.
Fortunately third party restore apps do!
The real lesson is that if you are using an iPhone, please use a service like dropbox or google drive or one drive. In this manner if the backup is corrupt you don’t lose your data or spend money on someone tool.