Re: Hot Standby switchover

Hi,

Shoaib Mir <shoaibmir@gmail.com> writes:
> Now Hot-Standby is setup like this...
>
> A --> B 
> A --> C
>
> Now if I will like to do a switch so as to make B the new master and have my replication look like this:
>
> B --> C 
> B --> A
>
> Where are the steps I need for doing so?

First, you need a common archive somewhere all the 3 servers can read
it, and you need to setup the restore_command so that you can use it.

Now, you can change the primary_conninfo on C so that it connects to
B. I guess that means a restart. Note that you only want to do that once
server B is the new master, so has been triggered as such. That means a
change of TimeLine, though, so it'll break streaming : that's when you
need to read the WALs from the archive, with the restore_command.

Then, to have the old master A a slave of the new master B, you need to
do a full slave setup here, with base backup and all.

I hope we will be able to get cascading support in 9.1 or before so that
it's possible to simplify all this by having a "relay" server in the
mix, so that you only talk to this one when changing the master.

Of course enabling the old master as a slave would still need a full
setup from scratch. There has been thoughts on how to bypass the base
backup there on -hackers, rather promising, but I don't know of any work
having been done yet. Guys are getting 9.0 out the door for now :)

Regards,
--
dim