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https://issues.apache.org/jira/browse/ACCUMULO-623?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13429666#comment-13429666
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Josh Elser commented on ACCUMULO-623:
-------------------------------------
Interesting, I added some messages in TabletServer to dump those variables on
my instance: 'dfs.durable.sync'=false and 'dfs.support.append'=true. I have
neither set in my config files.
Cloudera's site (https://ccp.cloudera.com/display/CDHDOC/Incompatible+Changes)
states that starting in CDH3u4 dfs.support.append is true by default. Given
that I'm on CDH3u3, apparently that's a little off or I stumbled upon tlipcon's
magic pixie dust ;)
> Data lost with hdfs write ahead log
> -----------------------------------
>
> Key: ACCUMULO-623
> URL: https://issues.apache.org/jira/browse/ACCUMULO-623
> Project: Accumulo
> Issue Type: Bug
> Environment: MacOSX, Hadoop 1.0.3, zookeeper 3.3.3
> Reporter: Keith Turner
> Assignee: Keith Turner
> Priority: Blocker
> Fix For: 1.5.0
>
>
> I shut my machine down with Accumulo, Zookeeper, and HDFS running. When I
> restarted it, Accumulo failed to recover its write ahead log because it was
> zero length. I wondered if this was because I shutdown HDFS so I tried the
> following on my single node Accumulo instance.
> * start HDFS and zookeeper
> * init & start Accumulo
> * created a table and insert some data
> * pkill -f java
> * restart everything
> * Accumulo fails to start because walog is zero length
> Saw excpetions like the following
> {noformat}
> 06 18:58:44,581 [log.SortedLogRecovery] INFO : Looking at mutations from
> /accumulo/recovery/def72721-5c64-4755-87cc-2e8cfc3002b7 for !0;!0<<
> 06 18:58:44,590 [tabletserver.TabletServer] WARN : exception trying to assign
> tablet !0;!0<< /root_tablet
> java.lang.RuntimeException: java.io.IOException: java.lang.RuntimeException:
> Unable to read log entries
> at
> org.apache.accumulo.server.tabletserver.Tablet.<init>(Tablet.java:1458)
> at
> org.apache.accumulo.server.tabletserver.Tablet.<init>(Tablet.java:1295)
> at
> org.apache.accumulo.server.tabletserver.Tablet.<init>(Tablet.java:1134)
> at
> org.apache.accumulo.server.tabletserver.Tablet.<init>(Tablet.java:1121)
> at
> org.apache.accumulo.server.tabletserver.TabletServer$AssignmentHandler.run(TabletServer.java:2477)
> at
> org.apache.accumulo.core.util.LoggingRunnable.run(LoggingRunnable.java:34)
> at java.lang.Thread.run(Thread.java:680)
> Caused by: java.io.IOException: java.lang.RuntimeException: Unable to read
> log entries
> at
> org.apache.accumulo.server.tabletserver.log.TabletServerLogger.recover(TabletServerLogger.java:428)
> at
> org.apache.accumulo.server.tabletserver.TabletServer.recover(TabletServer.java:3206)
> at
> org.apache.accumulo.server.tabletserver.Tablet.<init>(Tablet.java:1426)
> ... 6 more
> Caused by: java.lang.RuntimeException: Unable to read log entries
> at
> org.apache.accumulo.server.tabletserver.log.SortedLogRecovery.findLastStartToFinish(SortedLogRecovery.java:125)
> at
> org.apache.accumulo.server.tabletserver.log.SortedLogRecovery.recover(SortedLogRecovery.java:89)
> at
> org.apache.accumulo.server.tabletserver.log.TabletServerLogger.recover(TabletServerLogger.java:426)
> ... 8 more
> {noformat}
> When trying to run LogReader on the files, it prints nothing.
> {noformat}
> $ ./bin/accumulo org.apache.accumulo.server.logger.LogReader
> /accumulo/recovery/def72721-5c64-4755-87cc-2e8cfc3002b7
> 06 19:04:37,147 [util.NativeCodeLoader] WARN : Unable to load native-hadoop
> library for your platform... using builtin-java classes where applicable
> $ ./bin/accumulo org.apache.accumulo.server.logger.LogReader
> /accumulo/wal/127.0.0.1+40200/def72721-5c64-4755-87cc-2e8cfc3002b7
> $
> {noformat}
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