[ADMIN] Recover from failover

[Martin S]

Hello list,

May be this information is inside the documentation, but couldn't find it.

I'm doing some tests with postgres 9.1.1 and replication, and I was
wandering if there is some information about how to recover from a
failover.

Suppose I'm doing some kernel upgrades on the master, so in order to
avoid downtime, I promote the slave to become the master, and reboot
the old-master. Once the old-master is up and running again, I want it
to be the master as it was before. The problem are the updates and
inserts made while it was offline. Does it recovers automagically by
streaming or something? Do you have any procedures/recommendations to
do it?


Cheers,

Martin

[Kevin Grittner]

Post by Martin S
May be this information is inside the documentation, but couldn't find it.
I'm doing some tests with postgres 9.1.1 and replication, and I
was wandering if there is some information about how to recover
from a failover.

Does this page provide what you need?:

http://www.postgresql.org/docs/9.1/interactive/warm-standby-failover.html

-Kevin

[Jerry Sievers]

Post by Martin S
Hello list,
May be this information is inside the documentation, but couldn't find it.
I'm doing some tests with postgres 9.1.1 and replication, and I was
wandering if there is some information about how to recover from a
failover.
Suppose I'm doing some kernel upgrades on the master, so in order to
avoid downtime, I promote the slave to become the master, and reboot
the old-master. Once the old-master is up and running again, I want it
to be the master as it was before. The problem are the updates and
inserts made while it was offline. Does it recovers automagically by
streaming or something? Do you have any procedures/recommendations to
do it?

About the only way you can role reverse master and standby is to stop
immediate the master, online the standby and then config the old
master as a standby and point it to the new master.

Doing a normal stop on the original master before onlining the
standby, then making changes to the old master DB and you'll have to
refresh the old master from a base backup before putting it into
recovery.

Most admins will tell you to refresh the old master in either case to
be on the safe side. This is the conventional and guaranteed to work
approach.

HTH

Post by Martin S
Cheers,
Martin
--
http://www.postgresql.org/mailpref/pgsql-admin

--
Jerry Sievers
Postgres DBA/Development Consulting
e: ***@comcast.net
p: 305.321.1144

[Martin S]

On Mon, Dec 5, 2011 at 11:58 PM, white.heron white

Dear All,
As soon as the slave database server had been promoted to master. The
old-server master database should be promote to become slave server.
I believe database replication has been done by your vendor. In this case
the new master database server will replicate data with new slave database
server.
Once replication completed. You may unplug the new slave database server and
perform kernel operating system upgrade as standalone.
Regards,
MOHAMMAD ADLI BIN MT TAJUDIN
H/p number:  [phone]

Thanks for the replies guys.

I like your approach Jerry. Promoting the slave and configuring the
master to be slave before going down, so when ex-master comes up, it
gets updated.
Problem here seems to be changing configs for maintenance. One error
and you are screwed. Probably creating some script to make it more
automatic or something could be a good idea.


Cheers!

Martin