Backend reboot replication lost

[Michael Menge]

Hi

Quoting Willy Offermans <Willy at Offermans.Rompen.nl>:

> Dear cyrus friends,
>
> Once more my backend server was rebooted. I did not find any messages in my
> logs nor did I receive any screen messages, that the replication was
> stopped. I wonder what will happen in a production environment, when the
> server reboots without my notice. Replication will fail and I will not be
> able to guarantee full recovery. To my opinion this is unacceptable.
>
> Best would be to incorporate a message system about failure in the
> sync_client code.
>
> I found some entries in the logs of the backend server about access of the
> replication user: every 10 minutes the user logs on to the backend server.
> Most probably to replicate the mails. I might use this behavior as a sign
> of a working replication mechanism. It is only indirect, but it tells me
> that there is at least some activity from the client to the backend. I
> wonder why the user is logging on every 10 minutes. Does it mean that the
> mails, received for the last 9 minutes or so, are not replicated?
>
> I'm not very experience in coding, but I will try to dig into the
> sync_client code and see how things are organised.
>
> I restarted the replication by executing ``sync_client -r'' on the client.
> I do not even know if this is the right step to take to reactivate
> replication. Can someone confirm? I can see in the logs of the backend,
> that the replication user logs on every 10 minutes again. I take that as a
> positive sign, that ``sync_client -r'' restarts the replication, but I have
> no clue about inconsistencies or other possible checks.
>
>

If you have configured rolling replication, every change will be logged
to the {configdirectory}/sync/log file. The 'sync_client -r' will check
for this file, move it to {configdirectory}/sync/log-pid, process the file
and checks again for a new {configdirectory}/sync/log

If 'sync_client -r' is not running has crashed {configdirectory}/sync/log
will grow. So by checking the filesize of the log you know if you replic is
up to date.

If sync_client stops, and there is a log-pid file present,
you run "sync_client -r -f {configdirectory}/sync/log-pid"
and check that the exit code. If it is 0 you can remove the
log-pid file and restart 'sync_cliet -r', if not check the logs
for errors.





--------------------------------------------------------------------------------
M.Menge                                Tel.: (49) 7071/29-70316
Universität Tübingen                   Fax.: (49) 7071/29-5912
Zentrum für Datenverarbeitung          mail:  
michael.menge at zdv.uni-tuebingen.de
Wächterstraße 76
72074 Tübingen
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