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From "sankalp kohli (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-6157) Selectively Disable hinted handoff for a data center
Date Thu, 09 Jan 2014 07:21:59 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-6157?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13866406#comment-13866406
] 

sankalp kohli commented on CASSANDRA-6157:
------------------------------------------

Here are the problems and why i chose what we have. 
{'dc1', 'dc2'} and ['dc1', 'dc2'] - If you specify this, snake yaml does not accept it as
a string. It needs to be wrapped in "" like "{'dc1','dc2'}"

"dc1,dc2" or "dc1"- This can be done. In Java, this will come as a string dc1,dc2 or dc1(without
quotes") .
One of the problems with this is that if someone has a typo in true or false, it will treat
is as a data center name. I have to do something like
if (hinted_handoff_enabled.toLowerCase().equals("true") || hinted_handoff_enabled.toLowerCase().equals("false"))
{
      hinted_handoff_enabled_default = Boolean.parseBoolean(hinted_handoff_enabled);
} else {
   split it by , and get the dc names.
}

So if someone types it as true1, we will treat it as a data center name. 
If this is fine, I can do the changes. 



> Selectively Disable hinted handoff for a data center
> ----------------------------------------------------
>
>                 Key: CASSANDRA-6157
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-6157
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>            Reporter: sankalp kohli
>            Assignee: sankalp kohli
>            Priority: Minor
>             Fix For: 2.0.5
>
>         Attachments: trunk-6157-v2.diff, trunk-6157-v3.diff, trunk-6157-v4.diff, trunk-6157.txt
>
>
> Cassandra supports disabling the hints or reducing the window for hints. 
> It would be helpful to have a switch which stops hints to a down data center but continue
hints to other DCs.
> This is helpful during data center fail over as hints will put more unnecessary pressure
on the DC taking double traffic. Also since now Cassandra is under reduced reduncany, we don't
want to disable hints within the DC. 



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