Re: Replication recovery?

On Thu, May 17, 2012 at 11:10 PM, John Mudd <johnbmudd(at)gmail(dot)com> wrote:
> For example, I take it that if the master is unavailable then you
> switch to a slave. The former slave becomes the current master. When
> the original "master" is ready to run and network accessible then do
> you bring it online in slave mode and it syncs automatically with the
> current master?

No, you need to rebuild replica on the original master's machine from scratch.

> At which time you're almost back to normal. Once they
> are back in sync do people typically switch the roles back to the
> original designation of who's a slave and who's a master? It's not
> clear to me if the last step is necessary.

It is up to you. I usually switch back only when the original master's
hardware is more powerful.

> Well, that's assuming that the master comes back online with all the
> data it had when it went offline. If it comes back but all data was
> lost (a worst case scenario) then I assume I have to take the current
> master offline and use it to repopulate the recovering master from
> scratch, correct? But... if I have additional slaves then I could just
> take one of the current slaves offline, use it to rebuild the original
> master, and then bring both the slave and the reconstructed master
> (now also a slave) back online and both will sync with the current
> master.
>
> John
>
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Sergey Konoplev

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