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From Andras Szerdahelyi <andras.szerdahe...@ignitionone.com>
Subject Re: row cache re-fill very slow
Date Mon, 19 Nov 2012 21:45:16 GMT
Wei,

i'm using the off-heap ( serialised ) row cache and front the entire thing with memcached
in the middle layer ( to prevent the most actively requested rows from pressuring the Cassandra
heap ). If you ask how much the pointers to the off-heap memory will take.. time will tell
( it should be easy to calculate though ) It's been working out great.

Andras Szerdahelyi
Solutions Architect, IgnitionOne | 1831 Diegem E.Mommaertslaan 20A
M: +32 493 05 50 88 | Skype: sandrew84


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On 19 Nov 2012, at 22:23, Wei Zhu <wz1975@yahoo.com<mailto:wz1975@yahoo.com>>
 wrote:

Just curious Andras, how can you manage such a big row cache (10-15GB currently)? By recommendation,
you will have 10% of your heap as row cache, so your heap is over 100G?? The largest datastax
recommends is 8GB and it seems to be a hardcoded limit in cassandra-env.sh ( # calculate 1/4
ram and cap to 8192MB). Does you GC hold up with such a big heap? In my experience, full GC
could take over 20 seconds for such a big heap.



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