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From Oleg Proudnikov <>
Subject One or Two clusters?
Date Mon, 26 Mar 2012 14:22:43 GMT

Could someone please help me understand the benefits of having a single large cluster vs.
having two smaller clusters separated by the pattern of use? One, MOSTLY WRITE cluster could
incrementally accumulate large amounts of data throughout the day. The daily increment would
be processed, summarized and stored into the second READ cluster at night. Users would only
need to interact with the READ portion of the overall system mostly during the day. Writes
would be spread throughout the day and will be a function of user activity with some bulk
load activity from time to time.  WRITE portion of the database would be an order of magnitude
larger than the READ portion. READ portion would have an an order of magnitude higher traffic
except during periodic bulk loads.

On one hand, If I were to have a single cluster I would have more  resources for the users
and potentially better scalability. A single cluster may need fewer servers overall, provided
write activity does not affect reads... On the other hand, write activity and associated memory
consumption, GC, as well as maintenance riutines may affect READ system. The system will be
hosted on EC2.

I would appreciate any thoughts.


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