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From Jeremiah Jordan <>
Subject Re: Data retrieval inconsistent
Date Thu, 10 Nov 2011 21:30:59 GMT
I am pretty sure the way you have K1 configured it will be placed across 
both DC's as if you had large ring.  If you want it only in DC1 you need 
to say DC1:1, DC2:0.
If you are writing and reading at ONE you are not guaranteed to get the 
data if RF > 1.  If RF = 2, and you write with ONE, you data could be 
written to server 1, and then read from server 2 before it gets over there.

The differing on server times will only really matter for TTL's.  Most 
everything else works off comparing user supplied times.


On 11/10/2011 02:27 PM, Subrahmanya Harve wrote:
> I am facing an issue in 0.8.7 cluster -
> - I have two clusters in two DCs (rather one cross dc cluster) and two 
> keyspaces. But i have only configured one keyspace to replicate data 
> to the other DC and the other keyspace to not replicate over to the 
> other DC. Basically this is the way i ran the keyspace creation  -
>     create keyspace K1 with 
> placement_strategy='org.apache.cassandra.locator.SimpleStrategy' and 
> strategy_options = [{replication_factor:1}];
>     create keyspace K2 with 
> placement_strategy='org.apache.cassandra.locator.NetworkTopologyStrategy' 
> and strategy_options = [{DC1:2, DC2:2}];
> I had to do this because i expect that K1 will get a large volume of 
> data and i do not want this wired over to the other DC.
> I am writing the data at CL=ONE and reading the data at CL=ONE. I am 
> seeing an issue where sometimes i get the data and other times i do 
> not see the data. Does anyone know what could be going on here?
> A second larger question is  - i am migrating from 0.7.4 to 0.8.7 , i 
> can see that there are large changes in the yaml file, but a specific 
> question i had was - how do i configure disk_access_mode like it used 
> to be in 0.7.4?
> One observation i have made is that some nodes of the cross dc cluster 
> are at different system times. This is something to fix but could this 
> be why data is sometimes retrieved and other times not? Or is there 
> some other thing to it?
> Would appreciate a quick response.

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