Sony has created a version of the vFAT filesystem that it says works better in consumer electronic devices with removable USB mass storage devices. Unlike vFAT, the xvFAT filesystem will not induce a kernel panic if a USB storage device is removed during a write operation, Sony says.

vFAT first appeared in Windows 95, adding support for filenames longer than 8 characters to the FAT filesystem used in previous Microsoft operating systems. vFAT quickly became the lingua franca filesystem for floppy disks, and all kinds of other removable storage devices used in cameras and other consumer electronics products.

Sony says vFAT is a good choice for consumer electronics products, since all common operating systems support it, and consumers are familiar with it. xvFAT retains backward compatibility with vFAT, Sony says, while adding features that deal with the case where a user removes media containing a filesystem in use. These features include application notification, and cancellation of the I/O elevator for block devices.

Additionally, xvFAT includes Japanese filename support, “dirty flag” support, and TIME ZONE support, Sony says.

Sony has submitted the xvFAT filesystem to the collection of 2.4.20 Linux patches maintained by CELF (Consumer Electronics Linux Forum), an industry group devoted to improving Linux for CE applications. Sony also plans to re-factor the filesystem as a patch to the current stable 2.6 Linux tree, and submit it for inclusion in the mainstream kernel tree, it says.

Microsoft attempted to patent the FAT filesystem in December of 2003, saying it had developed the ubiquitous technology in 1976 and now wanted to charge consumer electronics device makers that used the ubiquitious technology. However, the patent was rejected by the US Patent office in September of 2004.

Additional details about xvFAT can be found in a downloadable introduction (PDF download), and in a post to the CELF webpage. A Japanese-language PowerPoint presentation is also available here (translators invited to contribute).

Thanks to Alan Carvalho de Assis for bringing this news to our attention.

 
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