RAC Storage

Storage Options for RAC

• CFS (Cluster File System) – Easy to manage but only available on some platforms.  Does not address striping and mirroring.
• RAW – Available on all platforms but difficult to manage. Does not address striping and mirroring.
• NFS – Easy to manage but only available on some platforms.  Does not address striping and mirroring.
• ASM (Automatic Storage Management) – Easy to manage, available on ALL platforms, and DOES address striping and mirroring.

CFS (Cluster Filesystems)

• The idea of CFS is to basically share file filesystems between nodes.
• Easy to manage since you are dealing with regular files.
• CFS is configured on shared storage.  Each node must have access to the storage in which the CFS is mounted.
• NOT available on all platforms.  Supported CFS solutions currently:
• OCFS on Linux and Windows (Oracle)
• DBE/AC CFS (Veritas)
• GPFS (AIX)
• Tru64 CFS (HP Tru64)
• Solaris QFS

RAW (character devices)

• Hard to manage since you are dealing with character devices and not regular files.
• Adding and resizing datafiles is not trivial.
• On some operating systems volume groups need to deactivated before LVs can be manipulated or added.

NFS (Network Filesystem)

• NOT available on all platforms.  Supported NFS solutions currently:
  
• Network Appliance
  
• Redhat Linux
  
• Fujitsu Primecluster
  
• Solaris Suncluster

ASM

• Stripes files rather than logical volumes.
• Enables online disk reconfiguration and dynamic rebalancing.
• Provides adjustable re balancing speed.
• Provides redundancy on a file basis.
• Supports only Oracle files.
• Is cluster aware.
• Is automatically installed as part of the base code set .