Red Hat Global File System is

The first native 64-bit cluster file system on Linux for enterprise workloads - support for x86, AMD64/EM64T, and Itanium

The most scalable enterprise cluster file system on Linux - supporting over 100 nodes

Tightly integrated with Red Hat Enterprise Linux (tracks kernel releases and is supported for the full lifetime)

The first open source (GPL) cluster file system for enterprise workloads

Fully POSIX-compliant, meaning applications don't have to be rewritten to use GFS

Red Hat GFS is commonly used in clusters of enterprise applications to provide high speed access to a consistent file system image across the server nodes. This allows the cluster nodes to simultaneously read and write to a single shared filesystem. Typical application clusters where Red Hat GFS is deployed today include:

Databases (including Oracle RAC) - View this whitepaper on the benefits of using GFS with Oracle RAC and install guide (updated for Oracle RAC 10g)

Application and web servers

In-house custom applications

High-performance compute clusters where NFS scalability and performance are key

Red Hat Global File System (GFS) is supported for use with Red Hat Enterprise Linux AS, Red Hat Enterprise Linux WS, and Red Hat Enterprise Linux ES on x86, AMD64/EM64T and Itanium. Like all Red Hat solutions, it is delivered through Red Hat Network on an annual subscription basis.