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From Alex Karasulu <aok...@bellsouth.net>
Subject Re: [replication] Master slave replication will not suffice
Date Thu, 24 Feb 2005 18:03:02 GMT
Alan D. Cabrera wrote:

>
>
> David Boreham wrote:
>
>>> Cool, this sounds interesting.  Let's say that server A gets an 
>>> update to change foo=dog and and the same time server B gets an 
>>> update to change foo=cat.  Replication takes a while and 15 minutes 
>>> later, A gets the update to change foo=cat from B and B gets the 
>>> update to change foo=dog.  How does that get resolved?
>>
>>
>>
>> One of them wins. There are various possible choices,
>> however you might find it useful to think of a 'principle
>> of least surprise' here. e.g. if the change made later
>> in time wins, that might be less of a surprise than if
>> an earlier change wins.
>>
> How do we synchronize their clocks?
>
Ahha! :D - that's why we got an NTP service in this diagram an in SVN:

http://incubator.apache.org/directory/images/50k-ft-architecture.png

Also as image map on the front page here:

http://incubator.apache.org/directory/

(Oh btw Enrique looks like the move of some protocol stuff broke image 
map links to the repo)

http://svn.apache.org/viewcvs.cgi/incubator/directory/protocols/ntp/trunk/

-Alex




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