[HDFS-8245] Standby namenode doesn't process DELETED_BLOCK if the add block request is in edit log.

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.6.0
• Fix Version/s: 2.6.1, 2.8.0, 2.7.1, 3.0.0-alpha1
• Labels: 2.6.1-candidate BB2015-05-TBR
• Target Version/s: 2.8.0
• Hadoop Flags: Reviewed
• Assignee: Rushabh Shah
• Reporter: Rushabh Shah
• Created: 24/Apr/15 19:00
• Updated: 06/Jan/17 01:28
• Resolved: 08/May/15 21:39

Description

The following series of events happened on Standby namenode :
2015-04-09 07:47:21,735 [Edit log tailer] INFO ha.EditLogTailer: Triggering log roll on remote NameNode Active Namenode (ANN)
2015-04-09 07:58:01,858 [Edit log tailer] INFO ha.EditLogTailer: Triggering log roll on remote NameNode ANN

The following series of events happened on Active Namenode:,
2015-04-09 07:47:21,747 [IPC Server handler 99 on 8020] INFO namenode.FSNamesystem: Roll Edit Log from Standby NN (SNN)
2015-04-09 07:58:01,868 [IPC Server handler 18 on 8020] INFO namenode.FSNamesystem: Roll Edit Log from SNN

The following series of events happened on datanode ( datanodeA ):
2015-04-09 07:52:15,817 [DataXceiver for client DFSClient_attempt_1428022041757_102831_r_000107_0_1139131345_1 at /xxxx:51078 [Receiving block BP-595383232-xxxx-1360869396230:blk_1570321882_1102029183867]] INFO datanode.DataNode: Receiving BP-595383232-xxxx-1360869396230:blk_1570321882_1102029183867 src: /client:51078 dest: /datanodeA:1004

2015-04-09 07:52:15,969 [PacketResponder: BP-595383232-xxxx-1360869396230:blk_1570321882_1102029183867, type=HAS_DOWNSTREAM_IN_PIPELINE] INFO DataNode.clienttrace: src: /client:51078, dest: /datanodeA:1004, bytes: 20, op: HDFS_WRITE, cliID: DFSClient_attempt_1428022041757_102831_r_000107_0_1139131345_1, offset: 0, srvID: 356a8a98-826f-446d-8f4c-ce288c1f0a75, blockid: BP-595383232-xxxx-1360869396230:blk_1570321882_1102029183867, duration: 148948385
2015-04-09 07:52:15,969 [PacketResponder: BP-595383232-xxxx-1360869396230:blk_1570321882_1102029183867, type=HAS_DOWNSTREAM_IN_PIPELINE] INFO datanode.DataNode: PacketResponder: BP-595383232-xxxx-1360869396230:blk_1570321882_1102029183867, type=HAS_DOWNSTREAM_IN_PIPELINE terminating
2015-04-09 07:52:25,970 [DataXceiver for client /<datanodeB> :52827 [Copying block BP-595383232-xxxx-1360869396230:blk_1570321882_1102029183867]] INFO datanode.DataNode: Copied BP-595383232-xxxx-1360869396230:blk_1570321882_1102029183867 to <datanodeB>:52827
2015-04-09 07:52:28,187 [DataNode: heartbeating to ANN:8020] INFO impl.FsDatasetAsyncDiskService: Scheduling blk_1570321882_1102029183867 file <path>/blk_1570321882 for deletion
2015-04-09 07:52:28,188 [Async disk worker #1482 for volume ] INFO impl.FsDatasetAsyncDiskService: Deleted BP-595383232-xxxx-1360869396230 blk_1570321882_1102029183867 file <path>/blk_1570321882

Then we failover for upgrade and then the standby became active.

When we did ls command on this file, we got the following exception:

15/04/09 22:07:39 WARN hdfs.BlockReaderFactory: I/O error constructing remote block reader.
java.io.IOException: Got error for OP_READ_BLOCK, self=/client:32947, remote=datanodeA:1004, for file <filename>, for pool BP-595383232-xxxx-1360869396230 block 1570321882_1102029183867
at org.apache.hadoop.hdfs.RemoteBlockReader2.checkSuccess(RemoteBlockReader2.java:445)
at org.apache.hadoop.hdfs.RemoteBlockReader2.newBlockReader(RemoteBlockReader2.java:410)
at org.apache.hadoop.hdfs.BlockReaderFactory.getRemoteBlockReader(BlockReaderFactory.java:815)
at org.apache.hadoop.hdfs.BlockReaderFactory.getRemoteBlockReaderFromTcp(BlockReaderFactory.java:693)
at org.apache.hadoop.hdfs.BlockReaderFactory.build(BlockReaderFactory.java:351)
at org.apache.hadoop.hdfs.DFSInputStream.blockSeekTo(DFSInputStream.java:576)
at org.apache.hadoop.hdfs.DFSInputStream.readWithStrategy(DFSInputStream.java:800)
at org.apache.hadoop.hdfs.DFSInputStream.read(DFSInputStream.java:847)
at java.io.DataInputStream.read(DataInputStream.java:100)
at org.apache.hadoop.io.IOUtils.copyBytes(IOUtils.java:78)
at org.apache.hadoop.io.IOUtils.copyBytes(IOUtils.java:52)
at org.apache.hadoop.io.IOUtils.copyBytes(IOUtils.java:112)
at org.apache.hadoop.fs.shell.CopyCommands$Merge.processArguments(CopyCommands.java:97)
at org.apache.hadoop.fs.shell.Command.processRawArguments(Command.java:190)
at org.apache.hadoop.fs.shell.Command.run(Command.java:154)
at org.apache.hadoop.fs.FsShell.run(FsShell.java:287)
at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:70)
at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:84)
at org.apache.hadoop.fs.FsShell.main(FsShell.java:340)

Eventually this request was served by datanodeB on the second attempt,
15/04/09 22:07:39 INFO hdfs.DFSClient: Successfully connected to datanodeB:1004 for BP-595383232-xxxx-1360869396230:blk_1570321882_1102029183867

On further analyzing this problem, I found that when datanodeA notified the namenode after deleting that block, the then ANN didn't queue delete request to PendingDNMessages.
So when the then SNN read the edits, it didn't knew that the block from datanodeA was deleted.