Re: streaming replication breaks horribly if master crashes

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Heikki Linnakangas wrote:

>
> We're not talking about a timeout for promoting standby to master. The
> problem is that the standby doesn't notice that from the master's point
> of view, the connection has been broken. Whether it's because of a
> network error or because the master server crashed doesn't matter, the
> standby should reconnect in any case. TCP keepalives are a perfect fit,
> as long as you can tune the keepalive time short enough. Where "Short
> enough" is up to the admin to decide depending on the application.
>
>

I tested this yesterday and I could not get any reaction from the wal
receiver even after using minimal values compared to the default values .

The default values in linux for tcp_keepalive_time, tcp_keepalive_intvl
and tcp_keepalive_probes are 7200, 75 and 9. I reduced these values to
60, 3, 3 and nothing happened, it continuous with status ESTABLISHED
after 60+3*3 seconds.

I did not restart the network after I changed these values on the fly
via /proc. I wonder if this is the reason the connection didn't die
neither with the new keppalive values after the connection was broken. I
will check this later today.

regards,
- --
Rafael Martinez, <r(dot)m(dot)guerrero(at)usit(dot)uio(dot)no>
Center for Information Technology Services
University of Oslo, Norway

PGP Public Key: http://folk.uio.no/rafael/
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