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From "Cardon, Tejay E" <tejay.e.car...@lmco.com>
Subject Failing Tablet Servers
Date Thu, 20 Sep 2012 21:05:51 GMT
I'm seeing some strange behavior on a moderate (30 node) cluster.  I've got 27 tablet servers
on large dell servers with 30GB of memory each.  I've set the TServer_OPTS to give them each
10G of memory.  I'm running an ingest process that uses AccumuloInputFormat in a MapReduce
job to write 1,000 rows with each row containing ~1,000,000 columns in 160,000 families. 
The MapReduce initially runs quite quickly and I can see the ingest rate peak on the  monitor
page.  However, after about 30 seconds of high ingest, the ingest falls to 0.  It then stalls
out and my map task are eventually killed.  In the end, the map/reduce fails and I usually
end up with between 3 and 7 of my Tservers dead.

Inspecting the tserver.err logs shows nothing, even on the nodes that fail.  The tserver.out
log shows a java OutOfMemoryError, and nothing else.  I've included a zip with the logs from
one of the failed tservers and a second one with the logs from the master.  Other than the
out of memory, I'm not seeing anything that stands out to me.

If I reduce the data size to only 100,000 columns, rather than 1,000,000, the process takes
about 4 minutes and completes without incident.

Am I just ingesting too quickly?

Thanks,
Tejay Cardon

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