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From:Ricardo Freitas Date:October 27 2011 10:07am
Subject:RE: Master-Master -> duplicate entry
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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?


-----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/




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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