B should be the only one with a bad replication position, since it was replicating when A
crashed. So just adjust B, and A should catch up as normal (provided you have the last
24 hours of binlogs on B for A to read )
Regards,
Gavin Towey
-----Original Message-----
From: Bryan Cantwell [mailto:bcantwell@stripped]
Sent: Wednesday, October 07, 2009 11:12 AM
To: Gavin Towey
Cc: mysql@stripped
Subject: Re: Replication recovery
When only one machine dies I do send the new master position info to the
still running slave, and yes, it does the trick.
My main challenge is when A dies and is dead for 24 hours and then B
dies too. Now A is already out of synch with B and now B has a new log
position... Doesnt this make A now have a huge gap in data? How do I get
A up to date with B?
thx,
Bryancan
On 10/07/2009 12:53 PM, Gavin Towey wrote:
> In the case that one machine has a power failure, then starts a new binlog, you just
> have to set the slave to start replicating from the beginning of that binlog. That's easy
> to detect and repair with a daemon script. Even if both machines die, it'll be a similar
> scenario.
>
> Regards,
> Gavin Towey
>
> -----Original Message-----
> From: Bryan Cantwell [mailto:bcantwell@stripped]
> Sent: Wednesday, October 07, 2009 10:47 AM
> To: mysql@stripped
> Subject: Replication recovery
>
> I have 2 - 5.0.51a mysql databases setup in a dual master scenario. A is
> master of B and vise versa...
> In Linux 2.6.26 (if that matters).
> Everything is great while all is running normally. But, when I am
> testing the system by creating disasterous scenarios, I find some
> challenges I hope to get overcome.
>
> Let's say 'A' machine's plug gets kicked out of the wall and so when
> mysql restarts it starts fresh bin-log and the slave 'B' does not
> realize this change and we are now out of sync. 'A', however will simply
> catch up to 'B' and there MAY not be a problem.
>
> Even worse, 'A' dies and no one does anything about it, then later 'B'
> dies. Now Someone finally comes along and restarts both machines at the
> same time and neither are on the 'same page' and are totally out of sync.
>
> How, without re-copying the datafiles and starting over (after
> determining the most up to date machine to use), can I bring both 'A'
> and 'B' to the same point so I can move forward?
>
> Thanks,
>
> Bryancan
>
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