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https://issues.apache.org/jira/browse/HDFS-503?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13048444#comment-13048444
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sri commented on HDFS-503:
--------------------------
Error in name node
ERROR org.apache.hadoop.hdfs.server.namenode.NameNode:
java.lang.RuntimeException: java.lang.ClassNotFoundException:
org.apache.hadoop.dfs.DistributedRaidFileSystem
at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:866)
at
org.apache.hadoop.fs.FileSystem.createFileSystem(FileSystem.java:1304)
at org.apache.hadoop.fs.FileSystem.access$100(FileSystem.java:65)
at org.apache.hadoop.fs.FileSystem$Cache.get(FileSystem.java:1328)
at org.apache.hadoop.fs.FileSystem.get(FileSystem.java:226)
at org.apache.hadoop.fs.FileSystem.get(FileSystem.java:109)
at org.apache.hadoop.fs.Trash.<init>(Trash.java:62)
at
org.apache.hadoop.hdfs.server.namenode.NameNode.startTrashEmptier(NameNode.java:292)
at
org.apache.hadoop.hdfs.server.namenode.NameNode.initialize(NameNode.java:288)
at
org.apache.hadoop.hdfs.server.namenode.NameNode.<init>(NameNode.java:434)
at
org.apache.hadoop.hdfs.server.namenode.NameNode.createNameNode(NameNode.java:1153)
at
org.apache.hadoop.hdfs.server.namenode.NameNode.main(NameNode.java:1162)
Caused by: java.lang.ClassNotFoundException:
org.apache.hadoop.dfs.DistributedRaidFileSystem
at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:334)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:264)
at
org.apache.hadoop.conf.Configuration.getClassByName(Configuration.java:819)
at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:864)
... 11 more
Can some body help me out..
> Implement erasure coding as a layer on HDFS
> -------------------------------------------
>
> Key: HDFS-503
> URL: https://issues.apache.org/jira/browse/HDFS-503
> Project: Hadoop HDFS
> Issue Type: New Feature
> Components: contrib/raid
> Reporter: dhruba borthakur
> Assignee: dhruba borthakur
> Fix For: 0.21.0
>
> Attachments: raid1.txt, raid2.txt
>
>
> The goal of this JIRA is to discuss how the cost of raw storage for a HDFS
> file system can be reduced. Keeping three copies of the same data is very
> costly, especially when the size of storage is huge. One idea is to reduce
> the replication factor and do erasure coding of a set of blocks so that the
> over probability of failure of a block remains the same as before.
> Many forms of error-correcting codes are available, see
> http://en.wikipedia.org/wiki/Erasure_code. Also, recent research from CMU has
> described DiskReduce
> https://opencirrus.org/system/files/Gibson-OpenCirrus-June9-09.ppt.
> My opinion is to discuss implementation strategies that are not part of base
> HDFS, but is a layer on top of HDFS.
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