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From "Sylvain Lebresne (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (CASSANDRA-2609) Repair multi-DC awareness
Date Fri, 06 May 2011 07:08:03 GMT

     [ https://issues.apache.org/jira/browse/CASSANDRA-2609?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Sylvain Lebresne updated CASSANDRA-2609:
----------------------------------------

    Description: 
Repair has no multi-DC awareness in that if you have 2 DC with 3 replica in each, a repair
of a node will transit 3 merkle tree cross-DC and potentially initiate as many cross-DC streaming
(with likely a non null intersection between those). In theory, we could repair separately
in each DC, then repair between only two node cross-DC (that we know are up to date in their
respective DC) and finally re-repair in the separate DC (to pass the cross-DC changes to all
nodes of the DC).

It is yet unclear to me if we can make that efficient enough that it is worth the added complexity,
so this is really meant as an exploratory ticket. 

  was:
Repair has no multi-DC awareness in that if for instance you have 2 DC with 3 replica in each,
a repair of a node will transit 3 merkle tree cross-DC and potentially initiate as many cross-DC
streaming (with likely a non null intersection between those). In theory, we could repair
separately in each DC, then repair between only two node cross-DC (that we know are up to
date in their respective DC) and finally re-repair in the separate DC (to pass the cross-DC
changes to all nodes of the DC).

It is yet unclear to me if we can make that efficient enough that it is worth the added complexity,
so this is really met as an exploratory ticket. 


> Repair multi-DC awareness
> -------------------------
>
>                 Key: CASSANDRA-2609
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-2609
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>            Reporter: Sylvain Lebresne
>            Priority: Minor
>              Labels: ponies
>
> Repair has no multi-DC awareness in that if you have 2 DC with 3 replica in each, a repair
of a node will transit 3 merkle tree cross-DC and potentially initiate as many cross-DC streaming
(with likely a non null intersection between those). In theory, we could repair separately
in each DC, then repair between only two node cross-DC (that we know are up to date in their
respective DC) and finally re-repair in the separate DC (to pass the cross-DC changes to all
nodes of the DC).
> It is yet unclear to me if we can make that efficient enough that it is worth the added
complexity, so this is really meant as an exploratory ticket. 

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