I am currently running CentOS as well and have no issues. I believe your JVM 
settings are the culprit. AggressiveOpts should probably not be on at all. CMS 
IncrementalMode should be turned off as well in production.

- Cloudera CDH v3 B2
- CentOS 5.5 (Kernel: 2.6.18-194.8.1.el5). 
- Sun JVM 1.6.0_16
- JVM Opts: -XX:+UseConcMarkSweepGC -XX:CMSInitiatingOccupancyFraction=75 
-XX:MaxNewSize=64m -XX:NewSize=64m

________________________________________
From: Jinsong Hu [[email protected]]
Sent: Friday, August 13, 2010 1:27 PM
To: [email protected]
Subject: Fw: namenode crash

Hi, There:
  does anybody know of a good combination of centos version and jdk version 
that works stably ? I am using centos version

Linux  2.6.18-194.8.1.el5.centos.plus #1 SMP Wed Jul 7 11:45:38 EDT 2010
 x86_64 x86_64 x86_64 GNU/Linux

jdk version
Java(TM) SE Runtime Environment (build 1.6.0_17-b04)
Java HotSpot(TM) 64-Bit Server VM (build 14.3-b01, mixed mode)

and run the namenode with the following jvm config
-Xmx1000m  -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode 
-XX:+DisableExplicitGC -XX:+HeapDumpOnOutOfMemoryError -XX:+UseCompressedOops 
-XX:+DoEscapeAnalysis -XX:+AggressiveOpts  -Xmx2G

but it crashed silently after 16 hours.

I used jdk
Java(TM) SE Runtime Environment (build 1.6.0_20-b02)
Java HotSpot(TM) 64-Bit Server VM (build 16.3-b01, mixed mode)

with the same jvm config, and the namenode crashed in about 1 week. I searched 
internet and people say 1.6.0_18 is not good.
but does anybody can recommend a good combination of jdk and os version that 
can run stably ?


This crashing problem doesn't happen with a small cluster of 4 datanodes. but 
it happens with a cluster of 17 datanodes.

Jimmy.


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