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MQ_107747's avatar
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Feb 28, 2011

HASH ElECTION with different cache server Type

Dears ,



could you please someone help me to do hash election for different cache type pool ? for example i have 6 servers , 2 servers the capacity for them are up to 500 MB , and other 2 servers are up to 200M , and the last 2 servers are up to 100 M , and i am plan to use all of them under one VS (wild virtual server) with hash election mechanism , but how i can do some ratio to be for first bigger cache servers two times more than the other cache servers and so on , with hash election mechanism , really i will appreciate anyone can help !



thanks, MQ

4 Replies

  • Trying to wrap my feeble mind around your requirements. You say the servers are 500MB/200M/100M, is that per second, or storage capacity? If the former, you probably should look at rate classes, if the latter, you'd need to do a considerable amount of design work to make sure to get the right files into the right servers. Perhaps I misunderstand your scenario, though.
  • Hello Jason , first thanks for your trying to help !



    sorry for non complete picture, i will try to make it more clear , basically i have three different type of caches with different performance ( squid cache servers , bluecoat cache servers , and cache flow servers ) , i am planning to use election hash mechanism for all of them under one pool , but the issue here how i can do weight for each cache servers based on its performance.



    for example : ratio 1:2:4 respectivily based on its capacity.



    hope the picture become more clear now





  • the concepts of ratio and election hash are kind of at odds with each other, as one is purely based on performance and the other is purely based on deterministic outcomes. I'd really have to think about this one, but first thought is to pool only the like-performance servers, so you'd end up with a squidpool, a bluecoatpool, & and cacheflowpool. First, perform your ratio distribution between pools, then once a pool is selected, perform the election hash. In instances of failure, you could revert to another pool as necessary. This should take some careful planning and much testing...
  • i have did some work around solution that distribute to pools based on Client source IP address as follow:




    " ratio distribution between pools" sound seems good to me , do you have similar senario related to ratio between pools ?