Andrew Wang created HDFS-12567:
----------------------------------
Summary: 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
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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