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From Mick Semb Wever <...@apache.org>
Subject Re: OOM opening bloom filter
Date Mon, 12 Mar 2012 19:24:07 GMT

> > > > It's my understanding then for this use case that bloom filters are of
> > > > little importance and that i can


Ok. To summarise our actions to get us out of this situation, in hope
that it may help others one day, we did the following actions:

 1) upgrade to 1.0.7
 2) set fp_ratio=0.99
 3) set index_interval=4096
 4) restarted the node with Xmx30G
 5) run `nodetool scrub` 
      and monitor total size of bf files
      using `du -hc *-Filter.db | grep total`
 6) restart node with original Xmx setting once total bf size is under
      (scrub was running for >12hrs)
      (remaining bloom filters can be rebuilt later from normal compact)

Hopefully it will also eventuate that this cluster can run with a more
normal Xmx4G rather than the previous Xmx12G.

(2) and (3) are very much dependent on our set up using hadoop where all
reads are get_range_slice with 16k rows per request. Both could be tuned
correctly but they're the numbers that worked first up.

~mck

-- 
"When there is no enemy within, the enemies outside can't hurt you."
African proverb 

| http://github.com/finn-no | http://tech.finn.no |

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