If you need to backup the data on your current hard drive, follow the instructions in this step. Otherwise, continue to the next step.

On a Windows/OS X/Linux machine, format an external USB hard drive (with enough space available to backup your current hard content) into the FAT32 file system.

Make sure it's formatted FAT32. The Playstation 3 backup utility will not recognize any other file system.

Connect your formatted hard drive to the Playstation 3 through a USB port and power the console up.

Navigate the XMB to the 'Settings' menu and select 'System Settings'

Select the 'Backup Utility' function to create a backup of your data - this can take up to 2 hours if you have a lot of data on the PS3.