Oracle extended RAC for geographical disaster
Oracle Database Tips by Donald Burleson
What are the best options for a geographically distributed
disaster recovery using RAC? Can I use Data Guard or
Streams for disaster recovery?
Yes, you can always use Streams or Data Guard for Disaster
recovery, but if you have a distance of less than 90 miles, you
can use a geographically distributed RAC cluster.
distributed RAC you need a super-fast interconnect (e.g. "dark fiber" fiber
channel connectivity) you can have geographically distributed
RAC nodes, but a more common alternative to extended RAC is to use
Data Guard or Streams (n-way replication) for disaster recovery.
For shops with high capital
funding (lotsa cash), you can employ Dense Wavelength Division
Multiplexing (DWDM) technology or dark fiber, but it becomes very expensive
over long geographical distances.
The choice depends mostly on costs
and the volume of updates (DML) for the RAC cluster, plus your
tolerance for unplanned outages during a disaster. For
enough money, you can guarantee continuous availability with
extended RAC clusters, but if you can afford a 30 minute
downtime, Data Guard or n-way Streams may be a better approach.
You can get
expert advise on your particular shop by calling BC for check my
Notes on Oracle disaster recovery approaches: