On Mon, Feb 21, 2011 at 10:00 PM, Fujii Masao <masao.fujii@xxxxxxxxx> wrote:
The trouble with postgres is there's no easy way to "demote" a master machine to a slave. You need to create a new master, back up its database, and restore it onto the slave before starting it. This seems difficult to implement, and pacemaker is already very complicated as it is.
We are seriously considering writing our own tool that simply tests the master from the slave, and runs a very simple shell script to take over if necessary.
Cheers,
Jody
The resource agents for MySQL and DRBD have been implemented as
master/slave ones. So I think that the resource agent for PostgreSQL also
should be done the same way, i.e., you should implement only "start" and
"stop" but also "promote" and "demote".
The trouble with postgres is there's no easy way to "demote" a master machine to a slave. You need to create a new master, back up its database, and restore it onto the slave before starting it. This seems difficult to implement, and pacemaker is already very complicated as it is.
We are seriously considering writing our own tool that simply tests the master from the slave, and runs a very simple shell script to take over if necessary.
Cheers,
Jody
