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From:navid@navid.it Date:October 27 2011 10:16am
Subject:Re: Master-Master -> duplicate entry
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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/
Thread
Master-Master -> duplicate entryRicardo Freitas26 Oct
  • Re: Master-Master -> duplicate entrynavid@navid.it26 Oct
    • Re: Master-Master -> duplicate entryRicardo26 Oct
  • Re: Master-Master -> duplicate entryRick James27 Oct
    • Re: Master-Master -> duplicate entryRicardo27 Oct
      • Re: Master-Master -> duplicate entryMarcus Bointon27 Oct
        • Re: Master-Master -> duplicate entryJohan De Meersman27 Oct
          • Re: Master-Master -> duplicate entryRicardo27 Oct
          • Re: Master-Master -> duplicate entryRicardo27 Oct
          • Re: Master-Master -> duplicate entryMarcus Bointon27 Oct
            • RE: Master-Master -> duplicate entryRicardo Freitas27 Oct
              • Re: Master-Master -> duplicate entrynavid@navid.it27 Oct
              • Re: Master-Master -> duplicate entryMarcus Bointon27 Oct
                • RE: Master-Master -> duplicate entryRicardo Freitas27 Oct
                  • Re: Master-Master -> duplicate entryMarcus Bointon27 Oct
                    • RE: Master-Master -> duplicate entryRicardo Freitas27 Oct
                    • Re: Master-Master -> duplicate entryRicardo27 Oct
                      • Re: Master-Master -> duplicate entryMarcus Bointon27 Oct
                        • RE: Master-Master -> duplicate entryRicardo Freitas27 Oct
                          • Re: Master-Master -> duplicate entryMarcus Bointon27 Oct
                            • Re: Master-Master -> duplicate entry (UUID lecture)Rick James27 Oct
            • Re: Master-Master -> duplicate entryJohan De Meersman28 Oct
        • Re: Master-Master -> duplicate entryRicardo27 Oct
  • Re: Master-Master -> duplicate entrylist27 Oct
    • RE: Master-Master -> duplicate entryRicardo Freitas27 Oct
      • Re: Master-Master -> duplicate entryMarcus Bointon27 Oct
        • Re: Master-Master -> duplicate entryMySQL)27 Oct
    • Re: Master-Master -> duplicate entryRick James27 Oct
      • Re: Master-Master -> duplicate entryMarcus Bointon27 Oct
        • Re: Master-Master -> duplicate entryRick James27 Oct
          • Re: Master-Master -> duplicate entryJohan De Meersman28 Oct
            • Re: Master-Master -> duplicate entryRick James28 Oct
              • Re: Master-Master -> duplicate entryMats Kindahl31 Oct
      • Re: Master-Master -> duplicate entrylist27 Oct