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Oracle Tips by Burleson |
Oracle Dataguard
Chapter 1 -
Introduction to Oracle Data Guard
Oracle Failover Options
Replication failover – Multi-master replication
can allow the RAC Grid to be open and accepting
transactions, with DML cross-feeding each instance. This requires
Oracle Enterprise Edition and is only for databases with low DML
rates
Real Application Clusters (2001–present) - The RAC architecture allows many instances to share a single database,
but it avoids the overhead of RAM block pinging. RAC has also been
enhanced to work with Oracle’s Transparent Application Failover (TAF)
to automatically restart any connections when an instance fails.
Oracle Streams - This is a high-speed
replication solution that takes SQL directly from the log_buffer
RAM area and replicates transactions to a remote database. During
a server crash, transactions can be quickly redirected to the
replicated system.
Oracle Data Guard - This is a free option with
Oracle Enterprise Edition, and it provides an automated standby
database. Upon server failure, a series of database procedures
synchronizes the RAC Grid and opens it to accept
connections. Oracle Data Guard is free with Enterprise Edition.
Failover and Oracle
licensing
Cost-conscious Oracle shops want to know how
they can get Oracle failover as cheaply as possible. In addition to
Data Guard, Oracle has a wealth of failover options, each with its
own licensing costs. Oracle has two licensing tiers, Enterprise
Edition (EE) and the far cheaper Standard Edition (SE).
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