postgres-xc-general Mailing List for Postgres-XC

I have several questions on your configuration.

1. Did you configure your XC cluster with pgxc_ctl?   If not, I'm afraid
pgxc_ctl may not work correctly if pgxc_ctl configuration file is exactly
matches your manual configuration.

2. I assume that you're configuring GTM high-available, because GTM slave
does not help if coordinator or datanode crashes.   It helps only when GTM
master fails.    When you find GTM master fails, you can issue gtm_ctl to
GTM slave to promote it to the new master.  (pgxc_ctl failover command will
take care of this process).

3. You need to configure GTM proxy to reconnect to the new master, or you
need to stop coordinator and datanode, configure their postgresql.conf
files to target to the new master, and restart it.  I recommend to
configure GTM proxy.   Pgxc_ctl provide reconnect command to change GTM
proxy target to the new master.

4. If you'd like to make coordinator/datanode high-available, you need
their slaves too.

Pgxc_ctl comes with 1.1 (and its beta).   Document will be available from
Postgres-XC project page.

Please do now hesitate to post further questions/issues.

Regards;
---
Koichi Suzuki



2013/8/19 Sean Hogan <se...@co...>

>  Hi,
>
> I am investigating Postgres-XC with the coordinators and data nodes on two
> servers.  My goal is primarily high availability rather than raw
> performance, so I was planning to use one coordinator and one datanode on
> each server, with the GTM master and slave elsewhere.  Just like on page 36
> of http://wiki.postgresql.org/images/4/44/Pgxc_HA_20121024.pdf.
>
> I've been trying to use pgxc_ctl (the C program, not the Bash script at
> https://github.com/koichi-szk/PGXC-Tools), but I'm having some conceptual
> problems with the failover process.  I understand that coordinator and
> datanode slaves are promoted and become identical to the former masters
> (true?), but I'm unclear what happens to the former masters.  "monitor all"
> no longer shows them.
>
> I suppose my question is: what do I need to do, to make the former masters
> into new slaves?  To me it would make sense to be able to failover node1
> once and then again, and be left with more or less the same configuration
> as in the beginning.  It would be okay if there is some magic command I can
> run to reconfigure a former master as the new slave.
>
> Are these reasonable expectations, or am I asking too much of the software?
>
> I also have a potential issue with what happens when one of my servers
> fails completely.  The master coordinators and datanodes are running with
> synchronous_commit = on and one value in synchronous_standby_names.
> Doesn't that mean that transactions on the good server's master coordinator
> and master datanode will block trying to replicate to their slaves on the
> dead server?
>
> Sorry if these are RTFM items, I couldn't find clear answers in any of the
> documentation.
>
> Thanks,
> Sean
>
>
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