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The following page has been changed by stack: http://wiki.apache.org/hadoop/Hbase/Troubleshooting The comment on the change is: Update ------------------------------------------------------------------------------ === Causes === * Slow datanodes are marked as down by DFSClient; eventually all replicas are marked as 'bad' (HADOOP-3831). === Resolution === + * Apply HADOOP-4681 to your cluster or at least to the hadoop jar used by hbase. * Try setting '''dfs.datanode.socket.write.timeout''' to zero (in hadoop 0.18.x -- See HADOOP-3831 for detail and why not needed in hadoop 0.19.x). See the thread at [http://mail-archives.apache.org/mod_mbox/hadoop-hbase-user/200810.mbox/%[email protected]%3e message from jean-adrien] for some background. Note, this is an hdfs client configuration so needs to be available in $HBASE_HOME/conf. Making the change only in $HADOOP_HOME/conf is not sufficient. Copy your amended hadoop-site.xml to the hbase conf directory or add this configuration to $HBASE_HOME/conf/hbase-site.xml. * Try increasing '''dfs.datanode.handler.count''' from its default of 3. This is a server configuration change so must be made in $HADOOP_HOME/conf/hadoop-site.xml. Try increasing it to 10, then by additional increments of 10. It probably does not make sense to use a value larger than the total number of nodes in the cluster. @@ -129, +130 @@ * In accordance with your hardware, tune your heap space / garbage collector settings in the HBASE_OPTS variable of {{{$HBASE_CONF/hbase-env.sh}}}. Try the ''concurrent garbage collector'' {{{(-XX:+UseConcMarkSweepGC)}}} to avoid to stop the threads during GC. Read these articles for more info about Hotspot GC settings * [http://java.sun.com/docs/hotspot/gc1.4.2/faq.html Garbage collector FAQ] Quick overview * [http://java.sun.com/javase/technologies/hotspot/gc/gc_tuning_6.html Tuning garbage collector in Java SE 6] - * For Java SE 6, some users have had success with {{{ -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:ParallelGCThreads=8 }}} + * For Java SE 6, some users have had success with {{{ -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:ParallelGCThreads=8 }}}. + * See HBase [wiki:PerformanceTuning Performance Tuning] for more on JVM GC tuning. [[Anchor(8)]] == 8. Problem: Instability on Amazon EC2 == @@ -158, +160 @@ <value>60000</value> </property> }}} - * For Java SE 6, some users have had success with {{{ -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:ParallelGCThreads=8 }}} + * For Java SE 6, some users have had success with {{{ -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:ParallelGCThreads=8 }}}. See HBase [wiki:PerformanceTuning Performance Tuning] for more on JVM GC tuning. [[Anchor(10)]] == 10. Problem: Scanners keep getting timeouts ==
