[pgpool-general: 3813] Re: Pgpool Watchdog and sharing information

Janusz Borkowski janusz.borkowski at infobright.com
Wed Jun 17 23:17:02 JST 2015


Hi!

If you can shutdown in an predefined order that the primary should get down as the last. Later start it first, then recover the others.
If the shutdown order is random, you can end up with several servers promoted to be primary. Then the one most recently shutdown should be started as primary, the others should use recovery procedure. If the computer clocks are reasonably in sync, then one can try to check logs to find out which one was shut down as the last one.

I am not sure if I got your problem properly, though...

Cheers!
J.


On 16.06.2015 17:24, Jose Baez wrote:
> Hi!
>
> In one of my scenarios DDBB servers need to shutdown from time to time (servers are mounted on a vehicle which has to shutdown servers when moving).
>
> *Question is about failover* and "sharing status information" (with master/master replication in PSQL).
>
> *If PSQL node fails* (which is running pgpool with watchdog *in standby mode* and a PSQL instance), the other PSQL node (with active Pgpool) will detect that one PSQL node has failed and, at same time, will send the Queries to the second PSQL node only.
>
> As the first node is stopped, first pgpool's watchdog hasn't been  able to receive the new status information.
>
> After a while, every vehicle's server get shuts down.
>
> When starting servers next time, if the first pgpool is the active one, it won't know about the most updated status information: *it will see both PSQL nodes as OK status*, won't it ? Which pgpool instance will run as active?
>
> Can i make both Pgpool to save/read the same "status_file" from a shared network drive... would it work if there is only 1 pgpool instance at same time? Does the file need specific permissions/owner?
>
>
> Is there a robust Pgpool configuration which involves shutting down servers often?  Would Streaming-Replication suits better?
>
> Thank you.
>
>
>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.sraoss.jp/pipermail/pgpool-general/attachments/20150617/430cc430/attachment.html>


More information about the pgpool-general mailing list