From: Rick James
Date: May 24 2012 11:41pm
Subject: RE: Architectural Help
List-Archive: http://lists.mysql.com/mysql/227533
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I deal with dozens of systems, all doing cross-country or cross-ocean repli=
cation.  The only viable approach (that we have deployed in production) is
* Dual-master, single writer -- That is, all 49 clients write to one machin=
e
* The two masters are geographically separate.
* Failover involves switching to the 'other' master.  It is _not_ fully aut=
omated.
* Slaves, as needed, scattered around the world -- This provides read scali=
ng.

1M writes per day -- that is an average of 12/sec.  Yawn.
Replication delay -- you probably will almost never see any.
Network outages -- one of many things that can cause trouble.  The sooner y=
ou write the data _and_ copy it to a _remote_ site, the sooner you are immu=
ne to floods, tornados, cyclones, power outages, motherboard death, etc.

> -----Original Message-----
> From: Anupam Karmarkar [mailto:sb_akarmarkar@stripped]
> Sent: Thursday, May 24, 2012 3:39 AM
> To: Nigel Wood
> Cc: mysql@stripped
> Subject: Re: Architectural Help
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> Dear Nigel,
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> Thank for reply..
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> See my comments below
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> --Anupam
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> ________________________________
>  From: Nigel Wood <nwood@stripped>
> To: Anupam Karmarkar <sb_akarmarkar@stripped>; "mysql@stripped"
> <mysql@stripped>
> Sent: Thursday, 24 May 2012 3:35 PM
> Subject: RE: Architectural Help
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> A few questions:
> which is more or a problem: network outages, network capacity or query
> latency?
> >>Network Outages is problem, between data centres
> When you say "near real-time" do you need transactional consistent view
> on all 49 servers or can some lag be tolerated?
> >>Some lag can be tolerated considering network outage
> Can any one of the 49 local servers potentially update/delete the same
> rows or data?
> >>Yes central server can update same row or local server but not at
> same time,=A0 Few data will be updated in central location and others
> majorly in local.One Application Writes in Centeral and Others in
> local, Local app and central app shares some data.
> Is there any natural segmentation point within the data?
> >>No
> Do the data centers have diverse networks so that connections to some
> data centers may remain when others?
> >>Yes, we have diverse nework , so connectivity will be avaiable in
> other data centers.
> In the event that a local data centre is totally isolated from the
> others what data should it be allowed to update?
> >>Loca application should always write in local database, Central
> Application Updated will not be available to local.
> Do your applications produce/examine=A0 large data set querying by
> secondary keys or using tull text search?
> >>We dont have text search or we dont query large data
> Are you in a position to modify the applications?
> >>No, Micro changes ok
> __________________________________
> From: Anupam Karmarkar [sb_akarmarkar@stripped]
> Sent: Thursday, May 24, 2012 10:17 AM
> To: mysql@stripped
> Subject: Architectural Help
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> Hi All,
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> I need architectural help for our requirement,
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> We have nearly 50 data centre through out different cities from these
> data center application connect to central database server currently,
> there are conectivity and nework flcutions issues for different data
> center, so we comeup with solution each data center we should have
> local database server which will keep syncing with other server so that
> application doesnt fail , User data can be updated in any of server and
> should reflect in every server.=A0 Application consists of
> write/read/delete operations,
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> Current writes each day central server 1million.
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> Only 1/1000 need to be distrubuted acrross servce rest need to be in
> central server.
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> How can we achive this ? solution needs very much real time data
> accepting nework lags.
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> Solution
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> Collect all changes in other 49 server into 1 central server(How can we
> collect data)
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> 49 keeps updating data into local database from central server(Using
> Repliation Can be done)
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> --Anupam
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> --
> MySQL General Mailing List
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