There are a series of edge cases that dictate the need for repair. The largest cases are 1) lost deletes 2) random disk corruptions 

In our use case we only delete entire row keys, and if the row key comes back it is not actually a problem because our software will find it an delete it again. In those places we dodge running repair believe it or not.

Edward 


On Fri, Apr 5, 2013 at 11:22 AM, Jean-Armel Luce <jaluce06@gmail.com> wrote:
Hi Cyril,

According to the documentation (http://wiki.apache.org/cassandra/Operations#Frequency_of_nodetool_repair), I understand that is is not necessary to repair every node before gc_grace_seconds if you are sure that you don't miss to run a repair each time a node is down longer than gc_grace_seconds.

"*IF* your operations team is sufficiently on the ball, you can get by without repair as long as you do not have hardware failure -- in that case, HintedHandoff is adequate to repair successful updates that some replicas have missed"

Am I wrong ? Thoughts ?




2013/4/4 <cscetbon.ext@orange.com>
Hi,

I know that deleted rows can reappear if "node repair" is not run on every node before gc_grace_seconds seconds. However do we really need to obey this rule if we run "node repair" on node that are down for more than max_hint_window_in_ms milliseconds ?

Thanks
-- 
Cyril SCETBON

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