Maximizing Filesystem Portability

Chapter 10, "Using Multiple OSs," includes information on filesystem compatibility across OSs. As described there, ext2fs is the most portable native Linux filesystem. Drivers and access tools for ext2fs are available in many different OSs, meaning that you can access ext2fs data from many non-Linux OSs. Unfortunately, most of these tools are limited in various ways—for instance, they may be access utilities rather than true drivers, they may not work with the latest versions of ext2fs, they may be able to read but not write ext2fs, or they may run a risk of causing filesystem

This document was created by an unregistered ChmMagic, please go to http://www.bisenter.com to regist* corruption when writing to ext2fs. Therefore, ext2fs's portability is limited.

Ext3fs is a journaling extension to ext2fs. (The next section, "Reducing Disk Check Times," describes journaling in more detail.) As such, many of the ext2fs access tools can handle ext3fs, although some disable write access on ext3 filesystems.

IBM wrote JFS for its AIX OS, and later ported it to OS/2. IBM then open sourced the OS/2 JFS implementation, leading to the Linux JFS support. This heritage makes JFS a good choice for systems that multiboot Linux and OS/2. There are compatibility issues, though. Most importantly, you must use 4,096-byte clusters to enable both OSs to use the same JFS partitions. There are also filename case-retention issues—OS/2 is case-insensitive, whereas Linux is case-sensitive. You can use JFS in a case-insensitive way from Linux, but this is only advisable on dedicated data-transfer partitions.

XFS, from Silicon Graphics' (SGI's) IRIX, is another migrant filesystem. Linux/IRIX dual-boot systems are rare, but you might want to use XFS as a compatibility filesystem on removable disks that move between Linux and IRIX systems. You can also use Linux's XFS support to read hard disks that originated on IRIX systems.

ReiserFS is currently the least portable of the major Linux-native filesystems. A BeOS version can be found at http://www.bebits.com/app/3214, but versions for other platforms have yet to appear, as of 2003. Therefore, you should avoid ReiserFS if you need cross-platform compatibility.

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