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https://issues.apache.org/jira/browse/KAFKA-188?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13486921#comment-13486921
]
Jun Rao commented on KAFKA-188:
-------------------------------
Our system tests fail with the latest patch.
python -B system_test_runner.py 2>&1 | tee test.out
Saw the following in broker log.
[2012-10-30 07:40:19,682] FATAL Fatal error during KafkaServerStable startup.
Prepare to shutdown (kafka.server.KafkaServerStartable)
java.io.IOException: No such file or directory
at java.io.UnixFileSystem.createFileExclusively(Native Method)
at java.io.File.createNewFile(File.java:883)
at kafka.utils.FileLock.<init>(FileLock.scala:12)
at kafka.log.LogManager$$anonfun$10.apply(LogManager.scala:64)
at kafka.log.LogManager$$anonfun$10.apply(LogManager.scala:64)
at
scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:206)
at
scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:206)
at
scala.collection.IndexedSeqOptimized$class.foreach(IndexedSeqOptimized.scala:34)
at scala.collection.mutable.ArrayOps.foreach(ArrayOps.scala:34)
at scala.collection.TraversableLike$class.map(TraversableLike.scala:206)
at scala.collection.mutable.ArrayOps.map(ArrayOps.scala:34)
at kafka.log.LogManager.<init>(LogManager.scala:64)
at kafka.server.KafkaServer.startup(KafkaServer.scala:60)
at
kafka.server.KafkaServerStartable.startup(KafkaServerStartable.scala:34)
at kafka.Kafka$.main(Kafka.scala:46)
at kafka.Kafka.main(Kafka.scala)
[2012-10-30 07:40:19,683] INFO [Kafka Server 1], shutting down
(kafka.server.KafkaServer)
> Support multiple data directories
> ---------------------------------
>
> Key: KAFKA-188
> URL: https://issues.apache.org/jira/browse/KAFKA-188
> Project: Kafka
> Issue Type: New Feature
> Reporter: Jay Kreps
> Attachments: KAFKA-188.patch, KAFKA-188-v2.patch, KAFKA-188-v3.patch,
> KAFKA-188-v4.patch, KAFKA-188-v5.patch, KAFKA-188-v6.patch
>
>
> Currently we allow only a single data directory. This means that a multi-disk
> configuration needs to be a RAID array or LVM volume or something like that
> to be mounted as a single directory.
> For a high-throughput low-reliability configuration this would mean RAID0
> striping. Common wisdom in Hadoop land has it that a JBOD setup that just
> mounts each disk as a separate directory and does application-level balancing
> over these results in about 30% write-improvement. For example see this claim
> here:
> http://old.nabble.com/Re%3A-RAID-vs.-JBOD-p21466110.html
> It is not clear to me why this would be the case--it seems the RAID
> controller should be able to balance writes as well as the application so it
> may depend on the details of the setup.
> Nonetheless this would be really easy to implement, all you need to do is add
> multiple data directories and balance partition creation over these disks.
> One problem this might cause is if a particular topic is much larger than the
> others it might unbalance the load across the disks. The partition->disk
> assignment policy should probably attempt to evenly spread each topic to
> avoid this, rather than just trying keep the number of partitions balanced
> between disks.
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