[jira] [Comment Edited] (CASSANDRA-11569) Track message latency across DCs

["stone (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSANDRA-11569?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15290374#comment-15290374 ] 

stone edited comment on CASSANDRA-11569 at 5/19/16 6:12 AM:
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see nodeLatency.PNG,I change latency from 90ms to 30ms at 10:50,and workload are same as usual.
but I cannot see the value changes rightnow.


I think may be I mistake the mean of metrics value.
there is not Instant value,but mean value.so I cant see the value changed right now when I increase the cross DC latency


was (Author: stone):
see nodeLatency.PNG,I change latency from 90ms to 30ms at 10:50,and workload are same as usual.
but I cannot see the value changes.

> Track message latency across DCs
> --------------------------------
>
>                 Key: CASSANDRA-11569
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-11569
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Observability
>            Reporter: Chris Lohfink
>            Assignee: Chris Lohfink
>            Priority: Minor
>         Attachments: CASSANDRA-11569.patch, CASSANDRA-11569v2.txt, nodeLatency.PNG
>
>
> Since we have the timestamp a message is created and when arrives, we can get an approximate time it took relatively easy and would remove necessity for more complex hacks to determine latency between DCs.
> Although is not going to be very meaningful when ntp is not setup, it is pretty common to have NTP setup and even with clock drift nothing is really hurt except the metric becoming whacky.



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