On Thu, Oct 27, 2011 at 11:07 AM, Ricardo Freitas <ricardo@stripped> wrote:
> So having a Master-Master where you only write to one Master (lets say the
> main one), you still need the increment and offset changed?
>
> My guess is no, right?
Only if you will never write to server B, but then what's the point of
having Master-Master?
If you don't set the auto-increment step and offset properly, the day
that you INSERT on server B you are likely to get a duplicate key
error.
-- Navid
> -----Original Message-----
> From: Marcus Bointon [mailto:marcus@stripped]
> Sent: quinta-feira, 27 de Outubro de 2011 10:55
> To: Replication replication
> Subject: Re: Master-Master -> duplicate entry
>
> On 27 Oct 2011, at 09:51, Johan De Meersman wrote:
>
>> Say what? If that's the case, you haven't set up your replication
> correctly. There are quite a few reasons to not use both masters
> concurrently, but this is not one of them.
>
> Not at all. The point of redundancy (via replication or DRBD) is to maintain
> consistent and available data in the face of a server or replication
> failure. If you only write to one master at a time you have that. If you
> write to both you have neither - i.e. it's actually worse than having no
> redundancy at all, hence my statement. Because there is no performance gain
> and there is an increased risk of data loss it's not just pointless, it's
> actively bad. It's a bit like using RAID-0, but without the speedup! With
> writes to both there's no way of avoiding the split-brain scenario you
> describe and it's really hard to recover from (I've been there!). No
> advantages plus lots of disadvantages sounds like a bad combo to me.
>
> There are some attempts to introduce a semi-synchronous replication system
> for MySQL that waits until transactions are replicated (possibly to a quorum
> of slaves, much like Cassandra) before committing (or at least before
> returning a result to the client).
>
> Marcus
> --
> Marcus Bointon
> Synchromedia Limited: Creators of http://www.smartmessages.net/
> UK info@hand CRM solutions
> marcus@stripped | http://www.synchromedia.co.uk/
