iPhone Info : File Storage
All iPods can function as mass storage devices to store data files. If the iPod is formatted on a Mac OS X computer it uses the HFS Plus file system format. If it is formatted on Windows, the FAT32 format is used because Windows cannot access HFS filesystems. The user must still use iTunes or a compatible third-party software to load audio, videos, and photos in such a way that they are playable and viewable on the iPod. Unlike most MP3 players, simply copying files to the drive will not allow the iPod to properly access them, however, with the use of open-source software, it is possible.
An iPod formatted as HFS Plus is able to serve as a boot disk for a Mac computer, allowing one to have a portable operating system installed. The older iPods with FireWire ports could additionally function in FireWire Disk Mode. With the advent of the Windows-compatible iPod, the iPod's default file system was switched from HFS Plus to FAT32, although they could be reformatted to either filesystem (excluding the iPod shuffle which is strictly FAT32).
iTunes cannot transfer songs or videos from device to computer, unless they were purchased from the iTunes Store and authorized for use on that computer[citation needed]. The media files are stored in a hidden folder together with a proprietary database on the iPod. While the hidden content can be accessed through the host operating system, practical recovery of the audio with correct file names, tag meta-data, and playlists requires the use of third-party software.
