Openswitch Failover

[Anish]

Hi, we are looking to implement openswitch to provide
continuity to our ASE database.
From what i have ready, openswitch will connect you to the
primary DB and move to the secondary if the prime DB fails.
So what happens if Openswitch fails, how can i double up on
opwnswitch. i will have openswitch installed on both my
hosted sites.

[Neal Stack]

Hello,

You are describing a redundant OpenSwitch environment.
You basically have two OpenSwitch instances. If one
of them crashes, the clients connected to that instance
must reconnect. You configure the client application's
interfaces (or sql.ini) file to have two "query" entries
so that if they try to connect to an OpenSwitch that is
down, they automatically (and silently) connect to the
second "query" entry.

I think the best description of this can be found here:
http://infocenter.sybase.com/help/index.jsp?topic=/com.sybase.help.openswitch_15.0.oswref/html/oswref/CHDEEDBH.htm

In 12.5.1, the two OpenSwitch instances did not communicate
with each other. This had the potential of causing some
problems if ASE also crashed while one of the OpenSwitch
instances were down. When you restarted the failed OpenSwitch,
two instances of OpenSwitch could be out of sync. In other
words, OpenSwitch A might think that ASE_ABC was up while
OpenSwitch B rightly knew that it was down and than ASE_XYZ
was now the primary server.

The chances of this happening are remote but in order to
over come this potential problem, 15.0 OpenSwitch introduced
a new feature called "mutually-aware". Basically, the
OpenSwitch instances communicate with each other so that
they always remain in sync. Details of this feature are
located here:
http://infocenter.sybase.com/help/index.jsp?topic=/com.sybase.help.openswitch_15.0.oswadmin/html/oswadmin/CJAIICHE.htm

Thanks,
Neal