Novell LINUX ENTERPRISE SERVER 10 - INSTALLATION AND ADMINISTRATION 04-08-2006 Installation Manual page 488

26.2.5 Reiser4
Right after kernel 2.6 had been released, the family of journaling file systems was joined
by another member: Reiser4. Reiser4 is fundamentally different from its predecessor
ReiserFS (version 3.6). It introduces the concept of plug-ins to tweak the file system
functionality and a finer grained security concept.
Fine Grained Security Concept
In designing Reiser4, its developers put an emphasis on the implementation of se-
curity-relevant features. Reiser4 therefore comes with a set of dedicated security
plug-ins. The most important one introduces the concept of file "items." Currently,
file access controls are defined per file. If there is a large file containing information
relevant to several users, groups, or applications, the access rights had be fairly
imprecise to include all parties involved. In Reiser4, you can split those files into
smaller portions (the "items"). Access rights can then be set for each item and each
user separately, allowing a much more precise file security management. A perfect
example would be /etc/passwd. To date, only root can read and edit the file
while non-root users only get read access to this file. Using the item concept of
Reiser4, you could split this file in a set of items (one item per user) and allow
users or applications to modify their own data but not access other users' data. This
concept adds both to security and flexibility.
Extensibility through Plug-Ins
Many file system functions and external functions normally used by a file system
are implemented as plug-ins in Reiser4. These plug-ins can easily be added to the
base system. You no longer need to recompile the kernel or reformat the hard disk
to add new functionalities to your file system.
Better File System Layout through Delayed Allocation
Like XFS, Reiser4 supports delayed allocation. See
(page 488). Using delayed allocation even for metadata can result in better overall
layout.
26.2.6 XFS
Originally intended as the file system for their IRIX OS, SGI started XFS development
in the early 1990s. The idea behind XFS was to create a high-performance 64-bit jour-
naling file system to meet the extreme computing challenges of today. XFS is very
488 Installation and Administration
Section 26.2.6, "XFS"