Question:
What is Oracle Fail Safe and how does it compare to Oracle RAC for
high availability? Can I use Fail Safe on Solaris or HP/UX?
Answer:
Oracle Fail Safe is a cheap alternative to RAC which only runs on
Windows. As such, it is far less reliable as a high availability
solution than Oracle RAC, primarily because of Windows vulnerabilities
and the tens of thousands of OS problems that require weekly patching
of Windows required by Microsoft.
Architecturally, Fail
Safe is very similar to RAC because it allows multiple instances to
share a common database, but RAC is far superior to Fail Safe for many
reasons.
·
Tiny servers:
Fail Safe cannot be run on industrial strength Sun, HP or IBM servers.
Remember, Fail Safe was designed to work on Windows PC’s.
·
Running instances:
In RAC, all instances are running and accepting work. In fail
safe, the failover instance must be started before it can be used,
causing an unnecessary outage.
·
Fast Failover:
In RAC, transparent application failover redirects transactions
immediately, while in Fail Safe you must wait for the instance and
listener to be started.
In sum, there is no
such thing as high availability on a Windows Fail Safe platform, not
because of Oracle, but because of the long history of Windows software
problems.
