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From "casablinca126.com" <casabli...@126.com>
Subject Re: Re: Why Cassandra performs better in 15 nodes than in 20 nodes?
Date Mon, 24 May 2010 03:04:23 GMT
hi,    
Have you checked the load-balancing of your 20 nodes? I have the similar experience that 3
nodes' performance is worse 
than 2 nodes'. The reason was bad load-balance; after reallocating data,  the performance
becomes expected. 

regards,
Cao Jiguang



2010-05-24 



casablinca126.com 



发件人: 史英杰 
发送时间: 2010-05-24  10:42:54 
收件人: user@cassandra.apache.org 
抄送: 
主题: Re: Why Cassandra performs better in 15 nodes than in 20 nodes? 
 
Hi,Jonathan 
  I am sorry that there is something wrong with the CL I said last time, I checked the test
code agagin. The version we used is 0.6.0-Beta3, and both the write and read CL are ConsistencyLevel.ONE.
 


2010/5/24 Jonathan Ellis <jbellis@gmail.com>

ZERO hasn't been the default CL for a long time.  You should upgrade
to 0.6.1.  (Read NEWS first to see what has changed.)


2010/5/23 史英杰 <shiyingjie1983@gmail.com>:
> The replication factor is 3, and the consistency level is default, zero.
>
> 在 2010年5月24日 上午7:25,Jonathan Shook <jshook@gmail.com>写道:
>>
>> It would be helpful to know the replication factor and consistency
>> levels of your reads and writes.
>>
>>
>> 2010/5/23 史英杰 <shiyingjie1983@gmail.com>:
>> > Thanks for your  reply!
>> > //Were all of those 20 nodes running real hardware (i.e. NOT VMs)?
>> > Yes, there are 20 real servers running in the cluster, and one
>> > Casssandra
>> > instance runs on each server.
>> > //Did your driver application(s) run on "real" hardware and how many
>> > threads
>> > did you use?
>> > The clients run on one server of the 20 servers, I used 10 threads to
>> > run
>> > the write and read tasks. How many threads can make Cassandra get good
>> > throughput?
>> >  Thanks!
>> > 2010/5/23 Mark Robson <markxr@gmail.com>
>> >>
>> >> On 23 May 2010 13:42, 史英杰 <shiyingjie1983@gmail.com> wrote:
>> >>>
>> >>> Hi, All
>> >>>    I am now doing some tests on Cassandra, and I found that both
>> >>> writes
>> >>> and reads on 15 nodes are faster than that of 20 nodes, how many
>> >>> servers
>> >>> does one Cassandra system contains during the real applications?
>> >>>    Thanks a lot !
>> >>>
>> >>>
>> >>> Yingjie
>> >>
>> >> I'd ask
>> >> Were all of those 20 nodes running real hardware (i.e. NOT VMs)?
>> >> and
>> >> Did your driver application(s) run on "real" hardware and how many
>> >> threads
>> >> did you use?
>> >> Cassandra can only get good throughput with a lot of client threads,
>> >> not
>> >> just a few.
>> >> Mark
>> >
>
>




--
Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of Riptano, the source for professional Cassandra support
http://riptano.com
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