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From Wayne Schroeder <>
Subject Never running repair: No need vs consequences in our usage pattern
Date Wed, 26 Nov 2014 20:16:48 GMT
I have a 30+ node cluster that is under heavy read and write load.  Based on the fact that
we never delete data, and all data is inserted with TTLs and is somewhat temporal if not upserted,
and we are fine with the consistency of one and read repair chance, we elected to never repair.
 The reasoning behind this is that the data is so temporal and would simply vanish through
normal compaction.  We also adhere to the policy of trying to do full row writes so we do
not have to do reassembly during reads.  Are there any consequences we should be aware of
with this strategy?  We don’t even run repair when adding nodes to the cluster—we just
wait for the data to invalidate itself via TTL and be compacted away.

Based on everything I’ve read, running repair only really helps us on consistency (which
we don’t care about because data is updated so often that being one update behind is fine)
and deleted data re-appearing (and we never delete, we just always use TTLs).  Perhaps there
is some other reason to run repair that we are not aware of?


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