[pgpool-general: 5190] Re: Architecture Questions

Muhammad Usama m.usama at gmail.com
Thu Dec 22 06:56:22 JST 2016

On Tue, Dec 20, 2016 at 10:24 PM, Yates, James C. -ND <
James.C.Yates.-ND at disney.com> wrote:

> What I’m concerned about is the corporate network link between the AWS
> regions going down and PgPool doing a failover.  Then I could have the East
> and West region both think they have a master and doing updates/inserts on
> each.  Then when the link comes back up, my databases are out of sync and I
> could lose data.

Yes, This is a valid point. Earlier I thought you were concerned about the
Watchdog going into the split-brain which is not likely to happen
especially in the active-active watchdog configurations.
Unfortunately, I can't think of any perfect solution for backend failover
in case of a network partitioning between East and West regions at the
moment, Can you please explain the availability requirements of your
application, Like when the regions are isolated from each other, is it okay
as per the requirements that the region that does not have the primary
PostgreSQL keeps offline until the link is restored?

Muhammad Usama

> On Dec 20, 2016, at 6:27 AM, Muhammad Usama <m.usama at gmail.com> wrote:
> Hi
> Can you please explain a little more about your concerns of the
> split-brain situation you want to avoid?
> As far as I understand from the architecture diagram the proposed
> deployment consists of four PostgreSQL servers (Two in each AWS
> availability zone) and the Pgpool-II servers in front of each PostgreSQL.
> And the Application servers can connect to any of the four available
> Pgpool-II, So this seems like an active-active Pgpool-II configuration.
> Which means you would not be using the floating-IP (delegate IP) with the
> Pgpool-II.
> So if this is correct and you are not planing to use the floating IP and
> master-standby configuration of Pgpool-II, What worries you about the
> split-brain?
> Thanks
> Best regards
> Muhammad Usama
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