Making a backup of your PI cards is an important function that you will need to be able to do, not just for this RetroPie purchase, but for all of the SD cards you may end up having in the future. Although Micro SD Cards are designed for years of reliable service… they are a “read and write” medium. The important part is that they “write”. That means they can be potentially damaged. An improper power down, static, or other physical problem can damage the card. But more often, they can be damaged by user actions that cause files to be misplaced, corrupted, deleted, or other problems. Any of these issues can break your RetroPie build. Being able to restore an SD Card back to a previous state will be important to keep your data safe, your RetroPie projects working smoothly.
Please see, “How to Care for Your RetroPie Micro SD Cards”, which is another page on this site.
Raspberry PI cards are always multi-partition formatted cards. They usually contain a FAT Partition used for booting, and a ext4 partition, used as a data container partition for the Raspberry PI OS and related files. PI cards can contain more than two partitions thought. My RetroPi cards contain two partitions.
Because of this, you can’t just insert the card in your PI, or in a windows or Mac and just copy all the files over to a new card. It will not work. But don’t worry, it really is not that hard to do… But, you will need special software installed on a separate Mac or Windows machine to make a copy. The software is called “Disk Imaging” software. It is software that makes a “image file” of all of the partitions and data on a disk drive, SD Card, or USB Flash drive. And, it stores everything as one file on the machine used for the backup. Once you have made an “image file” of your SD Card, you can then use that “image file” to create a duplicate of it, on to a new/blank SD Card… exactly like the original was when you made the image file originally. The software makes it easy. Also, you can write the image files to a larger card if you like, so that you have extra space on the new card.
There are many commercial and free disk imaging software applications out there, for both Mac, Windows, and Linux. Google searching “Raspberry PI Disk Image App Windows (or MAC)” or “Raspberry PI SD CARD backup app Mac (or Windows)” will show you lots of choices. Some are free, some are not.
I use a Mac, and I like an app called Balena Etcher. It is easy to use, and is not expensive, but it is not free. It works in trial mode for a while before you have to buy it. Balena Etcher work with Windows, Mac, and Linux.
The web site for it is:
http://www.balena.io/etcher/