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https://issues.apache.org/jira/browse/CASSANDRA-12257?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15388694#comment-15388694
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stone commented on CASSANDRA-12257:
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need measure the latency between DC real time so we can look back the data.
> data consistency of multi datacenter
> -------------------------------------
>
> Key: CASSANDRA-12257
> URL: https://issues.apache.org/jira/browse/CASSANDRA-12257
> Project: Cassandra
> Issue Type: Improvement
> Components: Coordination
> Reporter: stone
>
> Environment:
> serveral active-active cassandra datacenter.
> set write consistency level=local_quorum to get a high resquest response.
> Concern:
> we dont know the time of the data arrive other datacenter.
> we dont know the size of data that need to be transferred to other
> datacenter.
> Thought:
> 1.we can get the latency with ping or other monitor tool,but it can not
> represent the latency of cassandra data to be transferred from one dc to
> another dc.
> 2.we can measure the latency between dc.but there is a accumulated value from
> node started,it cannot represent the latency now.
> https://issues.apache.org/jira/browse/CASSANDRA-11569
> Scenanio:
> one project need to collect information from sensors,which in different
> region.2 datacenter,DC1,DC2.sensor1,sensor2 in DC1 region.sensor3,sensor4 in
> DC2.
> one client in DC1,pull data every 10 minutes.
> 1.sensor3 in DC2 write a record to DC2 at 8:59:55 ,and arrived DC1 at 9:00:05
> 2.client in DC1 pull data at 9:00,it should get the record,but it cannot as
> the
> record have not arrive DC1.
> 3.then client in DC1 will pull data at 9:10.it also can not get the record as
> it will pull data from 9:00---9:10,but the record created on 8:59:55
> so we will miss the record.
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