Instructions
Insert a USB media storage device into the PS3 console. While it is recommended that you primarily use memory cards designed for use with the PS3, you can use any sort of flash drive or memory stick, provided it uses a FAT32 file system.
Open the Backup Utility under the settings section of the PS3's hard disk.
Start the Backup option and your game data will automatically move to the storage device you select. The existing state of your game data will be moved onto the memory device. The data will be saved under [PS3]-[Export]-[Backup]. You can also restore your data from this menu and delete old backup data.
Remove the card and store it in a safe place. If your PlayStation 3 hard drive is ever damaged or destroyed, you can use the memory device to restore your game data. You can also bring the device to another PS3 and use your game data on a different console.