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From:Devananda Date:August 24 2004 4:42pm
Subject:Re: Doubts about cluster features
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Crouch, Luke H. wrote:

>you may specify any number (up to hundreds, I believe) of API nodes, which are typical
> mysql servers configured to use the cluster as their storage engine rather than their
> typical data files. in this way, you can have multiple mysql servers accepting connections
> and processing queries and all will have the same data. so you may round-robin or use some
> other method to balance your client connections to these servers and not worry about data
> consistency - it is handled by the cluster storage engine.
I believe there is currently a limit of 64 nodes in the cluster, 
counting each DB node, each API node, and the MGM node. I remember 
reading that this was an arbitrary compile time limit, but I haven't 
heard how to change it. Please correct me if I'm wrong, or if anyone 
knows how to change this I would be quite interested :)

To help try and explain how the cluster functions, as it is quite 
different from traditional mysql or oracle databases,  I'll attempt a 
little ASCII art (wish me luck!)

                    -- any number of normal database clients --
       -- it makes no difference which API node a client connects to --
        [ Apache/php clients ]                     [ any other normal 
mysql clients ]
                          /  |  \                                       
            /  |  \
[ API nodes]  @ @  @         @      @            @     @  @  @

-- here's part of the magic of the cluster, all of the api nodes are 
connected to all of the DB nodes automatically --
-- thus load balancing is performed internally across all the DB nodes --
-- it's up to you (the dba/programmer) to load balance across the API 
nodes though --

[ DB nodes ]         D                 D                   D               D
                            (D)              (D)                 (D)   
         (D)               [ NoOfReplicas = 2, 3 or 4 ] -- this gives 
you a built in failsafe
                                 if one of the DB nodes crashes, it's 
replica automatically and
                                 almost seamlessly picks up its load

                                                    \  |  /
                                            [ MGM node ]
-- the MGM node must be aware of all API and DB nodes, since it is the 
central management process (does lots of stuff) --

I hope that helps :)

Neopets, Inc
Doubts about cluster featuresRoberto Melo Cavalcante24 Aug
RE: Doubts about cluster featuresLuke H. Crouch24 Aug
  • Re: Doubts about cluster featuresDevananda24 Aug
    • Re: Doubts about cluster featuresMikael Ronström25 Aug