Re: [Postgres-xc-general] Split brain

[Nikhil S. <ni...@st...>]

Hi Chris,

Split brain is not solved internally by Postgres-XC. It's the job of
an external layer to ensure that such scenarios do not occur.

For example, one can use Corosync/Pacemaker to monitor XC nodes and
then use proper mechanisms to ensure failover and STONITH steps. CS/PM
solve the tricky problem of node membership and consistent cluster
view pretty well.

Regards,
Nikhils

On Tue, Mar 19, 2013 at 2:16 AM, Chris Brown <cb...@in...> wrote:
> Hi all,
>
> I just read through:
>
> wiki.postgresql.org/images/4/44/Pgxc_HA_20121024.pdf
>
> and I wanted to know how PG-XC solves the problem of split brain.
>
> For example, let's say there is a pair:
>   Box 1: datanode1-master, datanode2-slave, coordinator master, gtm master
>   Box 2: datanode1-slave, datanode2-master, coordinator slave, gtm slave
> and communication is severed between the two boxes.
>
> Another example:
>   Box 1: datanode1-master, datanode2-slave, coordinator master, gtm proxy
>   Box 2: datanode1-slave, datanode2-master, coordinator slave, gtm proxy
>   Box 3: gtm (no slave exists for simplicity)
> and communication is severed between box 1 and 2, but both can still
> communicate with box 3.  (Or another network outage scenario - there are
> obviously several.)
>
> Chris...
>
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