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From Jeremy Hanna <jeremy.hanna1...@gmail.com>
Subject Re: Massive writes when only reading from Cassandra
Date Sat, 10 Sep 2011 20:49:17 GMT
In addition, the mutation stage and the read stage are backed up like:

Pool Name                    Active   Pending   Blocked
ReadStage                        32       773         0
RequestResponseStage              0         0         0
ReadRepairStage                   0         0         0
MutationStage                   158    525918         0
ReplicateOnWriteStage             0         0         0
GossipStage                       0         0         0
AntiEntropyStage                  0         0         0
MigrationStage                    0         0         0
StreamStage                       0         0         0
MemtablePostFlusher               1         5         0
FILEUTILS-DELETE-POOL             0         0         0
FlushWriter                       2         5         0
MiscStage                         0         0         0
FlushSorter                       0         0         0
InternalResponseStage             0         0         0
HintedHandoff                     0         0         0
CompactionManager               n/a        29
MessagingService                n/a      0,34

On Sep 10, 2011, at 3:38 PM, Jeremy Hanna wrote:

> We are experiencing massive writes to column families when only doing reads from Cassandra.
 A set of 5 hadoop jobs are reading from Cassandra and then writing out to hdfs.  That is
the only thing operating on the cluster.  We are reading at CL.QUORUM with hadoop and have
written with CL.QUORUM.  Read repair chance is set to 0.0 on all column families.  However,
in the logs, I'm seeing flush after flush of memtables and compactions taking place.  Is there
something else that would be writing based on the above description?
> 
> Jeremy


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