我正在尝试使用以下方法测试一些需要 HDFS 的服务Docker 组成。由于被测试的服务、名称节点和数据节点都将在同一台物理机器（开发笔记本电脑）上运行，因此通过仅运行一个数据节点来减少内存使用量会很好。我正在使用这些 docker 镜像。
如果我运行一个名称节点和 3 个数据节点，一切都会按预期工作。我尝试通过在hdfs-site.xml两个节点中设置它来仅运行一个数据节点，并通过 compose 仅运行 1 个数据节点：
<property><name>dfs.replication</name><value>1</value></property>
它肯定会拾取这个，因为当它启动时我在日志中看到了这个：
blockmanagement.BlockManager: defaultReplication = 1
blockmanagement.BlockManager: maxReplication = 512
blockmanagement.BlockManager: minReplication = 1
blockmanagement.BlockManager: maxReplicationStreams = 2
blockmanagement.BlockManager: replicationRecheckInterval = 3000
第一次写入非常顺利。对于第二次写入，我得到了以下信息（在客户端应用程序上；Hadoop 端没有相关日志）：
java.io.IOException: Failed to replace a bad datanode on the existing pipeline due to no more good datanodes being available to try. (Nodes: current=[DatanodeInfoWithStorage[172.18.0.2:50010,DS-f97943bf-2cad-45e5-ae40-9ba947e54404,DISK]], original=[DatanodeInfoWithStorage[172.18.0.2:50010,DS-f97943bf-2cad-45e5-ae40-9ba947e54404,DISK]]). The current failed datanode replacement policy is DEFAULT, and a client may configure this via 'dfs.client.block.write.replace-datanode-on-failure.policy' in its configuration.
at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.findNewDatanode(DFSOutputStream.java:929)
at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.addDatanode2ExistingPipeline(DFSOutputStream.java:992)
at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.setupPipelineForAppendOrRecovery(DFSOutputStream.java:1160)
at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.run(DFSOutputStream.java:455)
此后每次写入都会在客户端和 HDFS 上出现此错误：
Failed to APPEND_FILE (whatever) for (client X) on 172.18.0.6 because this file lease is currently owned by (client Y) on 172.18.0.6
如果运行 3 个数据节点，这个问题就会神奇地消失。有人有在 docker 中运行一个名称节点和一个数据节点的经验吗？我那台可怜的小笔记本电脑无法处理 3 个数据节点的功率水平。
编辑：我试过了这个解决方案在这里。没用。现在我得到：
17:59:56 WARN hdfs.DFSClient: DataStreamer Exception
org.apache.hadoop.ipc.RemoteException(java.lang.UnsupportedOperationException): This feature is disabled. Please refer to dfs.client.block.write.replace-datanode-on-failure.enable configuration property.
at org.apache.hadoop.hdfs.protocol.datatransfer.ReplaceDatanodeOnFailure.checkEnabled(ReplaceDatanodeOnFailure.java:116)
at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.getAdditionalDatanode(FSNamesystem.java:3317)
at org.apache.hadoop.hdfs.server.namenode.NameNodeRpcServer.getAdditionalDatanode(NameNodeRpcServer.java:758)
[...]
HDFS 端的更完整日志（name是 namenode 和datadatanode；由于 docker-compose，日志的交错不是完全按时间顺序排列的）：
name | 16/10/03 18:03:43 INFO hdfs.StateChange: BLOCK* registerDatanode: from DatanodeRegistration(172.18.0.11:50010, datanodeUuid=8ad27f17-7a87-45cb-b782-981c2e7b6dc2, infoPort=50075, infoSecurePort=0, ipcPort=50020, storageInfo=lv=-56;cid=CID-22dd8c41-af12-41ad-81ef-832ebb10ec39;nsid=1117453574;c=0) storage 8ad27f17-7a87-45cb-b782-981c2e7b6dc2
name | 16/10/03 18:03:43 INFO blockmanagement.DatanodeDescriptor: Number of failed storage changes from 0 to 0
data | 16/10/03 18:03:43 INFO datanode.VolumeScanner: VolumeScanner(/hadoop/dfs/data, DS-593eb971-f0cc-4381-a2c7-0befbc4aa9e6): finished scanning block pool BP-1023406345-172.18.0.9-1475517812059
data | 16/10/03 18:03:43 INFO datanode.DataNode: Block pool Block pool BP-1023406345-172.18.0.9-1475517812059 (Datanode Uuid null) service to hadoop-nn1/172.18.0.9:8020 successfully registered with NN
data | 16/10/03 18:03:43 INFO datanode.DataNode: For namenode hadoop-nn1/172.18.0.9:8020 using DELETEREPORT_INTERVAL of 300000 msec BLOCKREPORT_INTERVAL of 21600000msec CACHEREPORT_INTERVAL of 10000msec Initial delay: 0msec; heartBeatInterval=3000
name | 16/10/03 18:03:43 INFO net.NetworkTopology: Adding a new node: /default-rack/172.18.0.11:50010
name | 16/10/03 18:03:44 INFO blockmanagement.DatanodeDescriptor: Number of failed storage changes from 0 to 0
data | 16/10/03 18:03:44 INFO datanode.VolumeScanner: VolumeScanner(/hadoop/dfs/data, DS-593eb971-f0cc-4381-a2c7-0befbc4aa9e6): no suitable block pools found to scan. Waiting 1814399359 ms.
data | 16/10/03 18:03:44 INFO datanode.DataNode: Namenode Block pool BP-1023406345-172.18.0.9-1475517812059 (Datanode Uuid 8ad27f17-7a87-45cb-b782-981c2e7b6dc2) service to hadoop-nn1/172.18.0.9:8020 trying to claim ACTIVE state with txid=1
name | 16/10/03 18:03:44 INFO blockmanagement.DatanodeDescriptor: Adding new storage ID DS-593eb971-f0cc-4381-a2c7-0befbc4aa9e6 for DN 172.18.0.11:50010
data | 16/10/03 18:03:44 INFO datanode.DataNode: Acknowledging ACTIVE Namenode Block pool BP-1023406345-172.18.0.9-1475517812059 (Datanode Uuid 8ad27f17-7a87-45cb-b782-981c2e7b6dc2) service to hadoop-nn1/172.18.0.9:8020
data | 16/10/03 18:03:44 INFO datanode.DataNode: Successfully sent block report 0x8b0c17676f1, containing 1 storage report(s), of which we sent 1. The reports had 0 total blocks and used 1 RPC(s). This took 16 msec to generate and 190 msecs for RPC and NN processing. Got back one command: FinalizeCommand/5.
name | 16/10/03 18:03:44 INFO BlockStateChange: BLOCK* processReport: from storage DS-593eb971-f0cc-4381-a2c7-0befbc4aa9e6 node DatanodeRegistration(172.18.0.11:50010, datanodeUuid=8ad27f17-7a87-45cb-b782-981c2e7b6dc2, infoPort=50075, infoSecurePort=0, ipcPort=50020, storageInfo=lv=-56;cid=CID-22dd8c41-af12-41ad-81ef-832ebb10ec39;nsid=1117453574;c=0), blocks: 0, hasStaleStorage: false, processing time: 2 msecs
name | 16/10/03 18:04:33 INFO hdfs.StateChange: DIR* completeFile: /XXX/appender/1475517840000/.write/172.18.0.6 is closed by DFSClient_NONMAPREDUCE_1250587730_30
data | 16/10/03 18:03:44 INFO datanode.DataNode: Got finalize command for block pool BP-1023406345-172.18.0.9-1475517812059
data | 16/10/03 18:04:34 INFO datanode.DataNode: Receiving BP-1023406345-172.18.0.9-1475517812059:blk_1073741825_1001 src: /172.18.0.6:39732 dest: /172.18.0.11:50010
data | 16/10/03 18:04:34 INFO DataNode.clienttrace: src: /172.18.0.6:39732, dest: /172.18.0.11:50010, bytes: 7421, op: HDFS_WRITE, cliID: DFSClient_NONMAPREDUCE_1250587730_30, offset: 0, srvID: 8ad27f17-7a87-45cb-b782-981c2e7b6dc2, blockid: BP-1023406345-172.18.0.9-1475517812059:blk_1073741825_1001, duration: 107663969
name | 16/10/03 18:04:33 INFO hdfs.StateChange: BLOCK* allocate blk_1073741825_1001{UCState=UNDER_CONSTRUCTION, truncateBlock=null, primaryNodeIndex=-1, replicas=[ReplicaUC[[DISK]DS-593eb971-f0cc-4381-a2c7-0befbc4aa9e6:NORMAL:172.18.0.11:50010|RBW]]} for /XXX/appender/1475517840000/172.18.0.6
name | 16/10/03 18:04:34 INFO namenode.FSNamesystem: BLOCK* blk_1073741825_1001{UCState=COMMITTED, truncateBlock=null, primaryNodeIndex=-1, replicas=[ReplicaUC[[DISK]DS-593eb971-f0cc-4381-a2c7-0befbc4aa9e6:NORMAL:172.18.0.11:50010|RBW]]} is not COMPLETE (ucState = COMMITTED, replication# = 0 < minimum = 1) in file /XXX/appender/1475517840000/172.18.0.6
name | 16/10/03 18:04:34 INFO BlockStateChange: BLOCK* addStoredBlock: blockMap updated: 172.18.0.11:50010 is added to blk_1073741825_1001{UCState=COMMITTED, truncateBlock=null, primaryNodeIndex=-1, replicas=[ReplicaUC[[DISK]DS-593eb971-f0cc-4381-a2c7-0befbc4aa9e6:NORMAL:172.18.0.11:50010|RBW]]} size 7421
name | 16/10/03 18:04:34 INFO hdfs.StateChange: DIR* completeFile: /XXX/appender/1475517840000/172.18.0.6 is closed by DFSClient_NONMAPREDUCE_1250587730_30
name | 16/10/03 18:04:45 INFO namenode.FSEditLog: Number of transactions: 14 Total time for transactions(ms): 21 Number of transactions batched in Syncs: 1 Number of syncs: 8 SyncTimes(ms): 17
name | 16/10/03 18:04:45 INFO hdfs.StateChange: DIR* completeFile: /XXX/appender/1475517840000/.write/172.18.0.6 is closed by DFSClient_NONMAPREDUCE_-1821674544_30
name | 16/10/03 18:04:48 WARN hdfs.StateChange: DIR* NameSystem.append: Failed to APPEND_FILE /XXX/appender/1475517840000/172.18.0.6 for DFSClient_NONMAPREDUCE_1129971636_30 on 172.18.0.6 because this file lease is currently owned by DFSClient_NONMAPREDUCE_-1821674544_30 on 172.18.0.6
hdfs.site.xml（名称节点）：
<configuration>
<property><name>dfs.namenode.name.dir</name><value>file:///hadoop/dfs/name</value></property>
<property><name>dfs.replication</name><value>1</value></property>
<property><name>dfs.namenode.rpc-bind-host</name><value>0.0.0.0</value></property>
<property><name>dfs.namenode.servicerpc-bind-host</name><value>0.0.0.0</value></property>
<property><name>dfs.namenode.http-bind-host</name><value>0.0.0.0</value></property>
<property><name>dfs.namenode.https-bind-host</name><value>0.0.0.0</value></property>
<property><name>dfs.client.use.datanode.hostname</name><value>true</value></property>
<property><name>dfs.datanode.use.datanode.hostname</name><value>true</value></property>
</configuration>
hdfs-site.xml（数据节点）：
<configuration>
<property><name>dfs.datanode.data.dir</name><value>file:///hadoop/dfs/data</value></property>
<property><name>dfs.replication</name><value>1</value></property>
<property><name>dfs.namenode.rpc-bind-host</name><value>0.0.0.0</value></property>
<property><name>dfs.namenode.servicerpc-bind-host</name><value>0.0.0.0</value></property>
<property><name>dfs.namenode.http-bind-host</name><value>0.0.0.0</value></property>
<property><name>dfs.namenode.https-bind-host</name><value>0.0.0.0</value></property>
<property><name>dfs.client.use.datanode.hostname</name><value>true</value></property>
<property><name>dfs.datanode.use.datanode.hostname</name><value>true</value></property>
</configuration>
答案1
我通过设置dfs.replication属性来修复它客户以及服务器。遇到此问题的人也应该尝试此方法。
对于那些好奇的人来说，这是我最终为他们使用的docker-compose文件（如果您需要在docker中快速设置hdfs，应该可以节省一些时间）：
version: "2"
networks:
platform: {}
services:
hdatanode:
image: "uhopper/hadoop-datanode"
networks:
platform:
aliases:
- "hdatanode"
environment:
CORE_CONF_fs_defaultFS: "hdfs://hadoop:8020"
CLUSTER_NAME: "cluster1"
HDFS_CONF_dfs_replication: "1"
depends_on:
- "hadoop"
hadoop:
image: "uhopper/hadoop-namenode"
networks:
platform:
aliases:
- "hadoop"
ports:
- "50070:50070"
- "8020:8020"
environment:
CLUSTER_NAME: "cluster1"
HDFS_CONF_dfs_replication: "1"
然后，如果在 docker 网络中运行，则在客户端上设置这三个配置属性：
<property><name>fs.defaultFS</name><value>hdfs://hadoop:8020</value></property>
<property><name>fs.hdfs.impl</name><value>org.apache.hadoop.hdfs.DistributedFileSystem</value></property>
<property><name>dfs.replication</name><value>1</value></property>
如果在 docker 网络之外运行，但你的 docker 位于 localhost 上，你需要将其更改为：
<property><name>fs.defaultFS</name><value>hdfs://localhost:8020</value></property>
<property><name>fs.hdfs.impl</name><value>org.apache.hadoop.hdfs.DistributedFileSystem</value></property>
<property><name>dfs.replication</name><value>1</value></property>
即时 HDFS 用于测试/开发目的！