1.2 Linux POSIX File Systems

The OES 2 Linux platform supports a variety of Linux POSIX file systems. It requires a Linux POSIX file system, such as Ext3, XFS, or Reiser, 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:

Table 1-1 Linux POSIX File Systems

Linux POSIX File System


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 move from Ext2 to Ext3, and vice versa, 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.

Journaled File System (JFS)

JFS was developed by IBM* to support high throughput server environments where performance is the ultimate goal. Because it is a full 64-bit file system, JFS supports both large files and partitions. It supports group commit of log entries for multiple concurrent operations, which improves journaling performance. It supports different directory organization for small and large directories and uses space efficiently.

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 File Systems in Linux in the SUSE Linux Enterprise Server 10 SP3 Installation and Administration Guide.

File System Primer describes the variety of file systems available on Linux and which ones are the best to use for which workloads and data.