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From Andrey Ilinykh <>
Subject Re: Nodetool Repair questions
Date Tue, 12 Aug 2014 22:10:33 GMT
1. You don't have to repair if you use QUORUM consistency and you don't
delete data.
2.Performance depends on size of data each node has. It's very difficult to
predict. It may take days.

Thank you,

On Tue, Aug 12, 2014 at 2:06 PM, Viswanathan Ramachandran <> wrote:

> Some questions on nodetool repair.
> 1. This tool repairs inconsistencies across replicas of the row. Since
> latest update always wins, I dont see inconsistencies other than ones
> resulting from the combination of deletes, tombstones, and crashed nodes.
> Technically, if data is never deleted from cassandra, then nodetool repair
> does not need to be run at all. Is this understanding correct? If wrong,
> can anyone provide other ways inconsistencies could occur?
> 2. Want to understand the performance of 'nodetool repair' in a Cassandra
> multi data center setup. As we add nodes to the cluster in various data
> centers, does the performance of nodetool repair on each node increase
> linearly, or is it quadratic ? The essence of this question is: If I have a
> keyspace with x number of replicas in each data center, do I have to deal
> with an upper limit on the number of data centers/nodes?
> Thanks
> Vish

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