Re: PG server clustering

On 10/17/2013 12:32 PM, Joseph Mays wrote:

We are assisting in the system administration of a partner that uses
PostGres in a mission critical position in their system. They have mail
servers and other things that rely on 24/7 availability for the postgres
server. They are running postgres 9.04 on redhat linux
(2.6.32-131.0.15.el6.x86_64). This is running on one old machine, and
thus does not really provide the liability they looking for.
I had the thought that I could set up another server as a slave, then
promote the slave in the event it’s necessary. I was trying I made a
system that watches for a change in the IP number number of the server
in dns, then downs the primary, swaps primary-secondary configs in the
primary, restarts the primary, then does the same in the secondary. This
actually worked on the first test from failing the primary to the
secondary. The problem came when I stried to switch it back. When I
tried to restart the original primary as secondary, it failed saying the
database was corrupted.

This is completely possible if configured correctly, we do this all the time for customers.

There are a couple of possible solutions to this, but I’m starting to
think that what they probably really want anyway is a Postgres server
cluster of two servers that stay in synch with each other, and can
simultaneously accept read and write requests. Are there any opinions
here about the best way to set this up?

There is no "good" way to do this. There are some application specific ways but it depends on their needs.

Joshua D. Drake


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