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Posted to hdfs-issues@hadoop.apache.org by "Andrew Wang (JIRA)" <ji...@apache.org> on 2017/10/04 23:40:00 UTC
[jira] [Updated] (HDFS-12567) BlockPlacementPolicyRackFaultTolerant
fails with racks with very few nodes
[ https://issues.apache.org/jira/browse/HDFS-12567?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Andrew Wang updated HDFS-12567:
-------------------------------
Attachment: HDFS-12567.001.patch
Patch attached.
This basically wraps the current logic with a fallback that removes the maxNodesPerRack limit when we fail to place enough racks. I used the earlier repro patch as the unit test, which now passes.
> BlockPlacementPolicyRackFaultTolerant fails with racks with very few nodes
> --------------------------------------------------------------------------
>
> Key: HDFS-12567
> URL: https://issues.apache.org/jira/browse/HDFS-12567
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: erasure-coding
> Affects Versions: 3.0.0-alpha1
> Reporter: Andrew Wang
> Assignee: Andrew Wang
> Labels: hdfs-ec-3.0-must-do
> Attachments: HDFS-12567.001.patch, HDFS-12567.repro.patch
>
>
> Found this while doing some testing on an internal cluster with an unusual setup. We have a rack with ~20 nodes, then a few more with just a few nodes. It would fail to get (# data blocks) datanodes even though there were plenty of DNs on the rack with 20 DNs.
> I managed to reproduce this same issue in a unit test, stack trace like this:
> {noformat}
> java.io.IOException: File /testfile0 could only be written to 5 of the 6 required nodes for RS-6-3-1024k. There are 9 datanode(s) running and no node(s) are excluded in this operation.
> at org.apache.hadoop.hdfs.server.blockmanagement.BlockManager.chooseTarget4NewBlock(BlockManager.java:2083)
> at org.apache.hadoop.hdfs.server.namenode.FSDirWriteFileOp.chooseTargetForNewBlock(FSDirWriteFileOp.java:286)
> at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.getAdditionalBlock(FSNamesystem.java:2609)
> at org.apache.hadoop.hdfs.server.namenode.NameNodeRpcServer.addBlock(NameNodeRpcServer.java:863)
> at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolServerSideTranslatorPB.addBlock(ClientNamenodeProtocolServerSideTranslatorPB.java:548)
> at org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos$ClientNamenodeProtocol$2.callBlockingMethod(ClientNamenodeProtocolProtos.java)
> at org.apache.hadoop.ipc.ProtobufRpcEngine$Server$ProtoBufRpcInvoker.call(ProtobufRpcEngine.java:523)
> at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:991)
> at org.apache.hadoop.ipc.Server$RpcCall.run(Server.java:869)
> at org.apache.hadoop.ipc.Server$RpcCall.run(Server.java:815)
> at java.security.AccessController.doPrivileged(Native Method)
> at javax.security.auth.Subject.doAs(Subject.java:422)
> at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1962)
> at org.apache.hadoop.ipc.Server$Handler.run(Server.java:2675)
> {noformat}
> This isn't a very critical bug since it's an unusual rack configuration, but it can easily happen during testing.
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