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From "Dwight Smith" <Dwight.Sm...@genesyslab.com>
Subject RE: Question regarding the need to run nodetool repair
Date Fri, 16 Nov 2012 00:34:14 GMT
Thanks

 

From: Edward Capriolo [mailto:edlinuxguru@gmail.com] 
Sent: Thursday, November 15, 2012 4:30 PM
To: user@cassandra.apache.org
Subject: Re: Question regarding the need to run nodetool repair

 



On Thursday, November 15, 2012, Dwight Smith
<Dwight.Smith@genesyslab.com> wrote:
> I have a 4 node cluster,  version 1.1.2, replication factor of 4,
read/write consistency of 3, level compaction. Several questions.
>
>  
>
> 1)      Should nodetool repair be run regularly to assure it has
completed before gc_grace?  If it is not run, what are the exposures?

Yes. Lost tombstones could cause deleted data to re appear.
>
> 2)      If a node goes down, and is brought back up prior to the 1
hour hinted handoff expiration, should repair be run immediately?

If node is brought up prior to 1 hour. You should let the hints replay.
Repair is always safe to run.
>
> 3)      If the hinted handoff has expired, the plan is to remove the
node and start a fresh node in its place.  Does this approach cause
problems?
>
You only need to join a fresh mode if the node was down longer then gc
grace. Default is 10 days.
>  
>
> Thanks
>
>

If you read and write at quorum and run repair regularly you can worry
less about the things above because they are essentially non factors. 


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