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From xavier manach <>
Subject Administration Memory for Noobs. (GC for ConcurrentMarkSweep ?)
Date Mon, 31 May 2010 13:32:18 GMT

  I search informations for basic tunning of memory in Cassandra.

My situation :
  I started to test larges imports of data in Cassandra 6.1.
My first import worked fine : 100 Millions row in 2 hours ~ around 10000
insert row by seconds
My second is slower with the same script in another column family :  ~
around 500 insert row by seconds...
I didn't understand why I have a lot of GC for ConcurrentMarkSweep.
[ GC for ConcurrentMarkSweep: 3437 ms, 104971488 reclaimed leaving 986519328
used; max is 1211170816. ]
( The max did'n't move, what is this value 1211170816 ? )
 I think the GC process appear when the insert is slow. The inserts didn't
work when the GC works ?

My machine has 66M of RAM, and the processor java only use around 1.8 %
How Can I optimise the use of memory ?
There is a the guideline for best performances ?


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