These kernels have support for the XFS file system from SGI.
You will also need to install the appropriate kernel-module-xfs-2.4.21-15.EL....

  kernel-2.4.21-15.EL.XFS.athlon.rpm
  kernel-2.4.21-15.EL.XFS.i686.rpm
  kernel-BOOT-2.4.21-15.EL.XFS.i386.rpm
  kernel-doc-2.4.21-15.EL.XFS.i386.rpm
  kernel-hugemem-2.4.21-15.EL.XFS.i686.rpm
  kernel-hugemem-unsupported-2.4.21-15.EL.XFS.i686.rpm
  kernel-smp-2.4.21-15.EL.XFS.athlon.rpm
  kernel-smp-2.4.21-15.EL.XFS.i686.rpm
  kernel-smp-unsupported-2.4.21-15.EL.XFS.athlon.rpm
  kernel-smp-unsupported-2.4.21-15.EL.XFS.i686.rpm
  kernel-source-2.4.21-15.EL.XFS.i386.rpm
  kernel-unsupported-2.4.21-15.EL.XFS.athlon.rpm
  kernel-unsupported-2.4.21-15.EL.XFS.i686.rpm

  kernel-module-xfs-2.4.21-15.EL.XFS-1.3.3-1.SL.athlon.rpm
  kernel-module-xfs-2.4.21-15.EL.XFS-1.3.3-1.SL.i686.rpm
  kernel-module-xfs-2.4.21-15.EL.XFSsmp-1.3.3-1.SL.athlon.rpm
  kernel-module-xfs-2.4.21-15.EL.XFSsmp-1.3.3-1.SL.i686.rpm

If you install one of the above kernels and you have openafs then you will
need to update to the appropriate one of these.

  kernel-module-openafs-2.4.21-15.EL.XFS-1.2.11-15.2.SL.athlon.rpm
  kernel-module-openafs-2.4.21-15.EL.XFS-1.2.11-15.2.SL.i686.rpm
  kernel-module-openafs-2.4.21-15.EL.XFSsmp-1.2.11-15.2.SL.athlon.rpm
  kernel-module-openafs-2.4.21-15.EL.XFSsmp-1.2.11-15.2.SL.i686.rpm

These are the user land utilities for XFS.

  acl-2.2.23-1.i386.rpm
  attr-2.4.16-1.i386.rpm
  dmapi-2.2.0-1.i386.rpm
  libacl-2.2.23-1.i386.rpm
  libattr-2.4.16-1.i386.rpm
  xfsdump-2.2.21-1.i386.rpm
  xfsprogs-2.6.13-1.i386.rpm
  libacl-devel-2.2.23-1.i386.rpm
  dmapi-devel-2.2.0-1.i386.rpm
  libattr-devel-2.4.16-1.i386.rpm
  xfsprogs-devel-2.6.13-1.i386.rpm

These were provided by CERN.  If you have any issues or questions send mail to
scientific-linux-devel@fnal.gov