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From Watanabe Maki <watanabe.m...@gmail.com>
Subject Re: 1.1.1 is "repair" still needed ?
Date Thu, 11 Oct 2012 10:55:15 GMT
Even if HH works fine, HH will not be created until the failure detector marks  the node is
dead. 
HH will not be created for partially timeouted mutation request ( but meets CL ) also... In
my understanding...


On 2012/10/11, at 5:55, Rob Coli <rcoli@palominodb.com> wrote:

> On Tue, Oct 9, 2012 at 12:56 PM, Oleg Dulin <oleg.dulin@gmail.com> wrote:
>> My understanding is that the repair has to happen within gc_grace period.
>> [ snip ]
>> So the question is, is this still needed ? Do we even need to run nodetool
>> repair ?
> 
> If Hinted Handoff works in your version of Cassandra, and that version
> is > 1.0, you "should" not need to repair if no node has crashed or
> been down for longer than max_hint_window_in_ms. This is because after
> 1.0, any failed write to a remote replica results in a hint, so any
> DELETE should eventually be fully replicated.
> 
> However hinted handoff is meaningfully broken between 1.1.0 and 1.1.6
> (unreleased) so you cannot rely on the above heuristic for
> consistency. In these versions, you have to repair (or read repair
> 100% of keys) once every GCGraceSeconds to prevent the possibility of
> zombie data. If it were possible to repair on a per-columnfamily
> basis, you could get a significant win by only repairing
> columnfamilies which take DELETE traffic.
> 
> https://issues.apache.org/jira/browse/CASSANDRA-4772
> 
> =Rob
> 
> -- 
> =Robert Coli
> AIM&GTALK - rcoli@palominodb.com
> YAHOO - rcoli.palominob
> SKYPE - rcoli_palominodb

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