1.2 Linux POSIX File Systems

The OES 11 SP2 platform supports a variety of Linux POSIX file systems. It requires a Linux POSIX file system, such as Btrfs, Ext3, Reiser, or XFS, for its system volume. The upper level of the kernel deals equally with these file systems through an abstract layer, the virtual file system (VFS). Some typical Linux POSIX file systems are described in Table 1-1. For more information, see Overview of Linux POSIX File Systems in the OES 11 SP2: Linux POSIX Volume Administration Guide.

Table 1-1 Linux POSIX File Systems

Linux POSIX File System

Description

Btrfs

Btrfs is a copy-on-write (COW) file system based on COW-friendly B-trees. It provides fault tolerance, repair, and easy management features.

Second Extended File System (Ext2)

Ext2 is a legacy file system with a solid reputation. It uses less memory than other options and is sometimes faster. Ext2 does not maintain a journal so it is not desirable to use it for any server that needs high availability.

Third Extended File System (Ext3)

Ext3 is a journaling file system that has the same data format and metadata format with its predecessor, Ext2. You can upgrade from Ext2 to Ext3 without rebuilding your file system. It also offers options to coordinate its metadata journaling with data writes.

Reiser File System (Reiser)

Reiser supports metadata journaling, but does not include data journaling or ordered writes. Its disk space utilization, disk access performance, and crash recovery are better than Ext2.

Extended File System (XFS)

XFS is a high-performance 64-bit journaling file system. It is good at manipulating large files and performs well on high-end hardware. XFS takes great care of metadata integrity. It supports independent allocation groups that can be addressed concurrently by the system kernel, which suits the needs of multiprocessor systems. It preallocates free space on the device to reduce file system fragmentation. However, delayed writes can result in data loss if the system crashes.

For more information, see the Overview of Linux POSIX File Systems in the OES 11 SP2: Linux POSIX Volume Administration Guide.