Question

我通过sqoop命令将数据从mysql成功上传到HDFS。

MySQL Hadoop群集

1 Namename的节点 1 Secondary NameNode的节点 1个Jobtracker节点 Datanade + Tasktracker的3个节点

之后我停止了hadoop集群。

再次启动Hadoop

在命令

下使用

  namenode -format (start NameNode)

  place new VERSION number in all datanode VERSION FILE

  now START DATANODE

启动datanode时，我在HDFS上传的MYSQL数据似乎丢失了。

以下是datanode日志的输出。

2014-05-15 07:46:56,018 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: Deleted blk_2445513848423894029_1337 at file /app/hadoop/data/dn/current/blk_2445513848423894029
2014-05-15 07:46:56,018 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: Deleted blk_3541234094053021888_1338 at file /app/hadoop/data/dn/current/blk_3541234094053021888
2014-05-15 07:46:56,018 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: Deleted blk_3862391472172526583_1347 at file /app/hadoop/data/dn/current/blk_3862391472172526583
2014-05-15 07:46:56,018 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: Deleted blk_4001223662527683746_1387 at file /app/hadoop/data/dn/current/blk_4001223662527683746
2014-05-15 07:46:56,018 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: Deleted blk_4143551839757190038_1410 at file /app/hadoop/data/dn/current/subdir14/blk_4143551839757190038
2014-05-15 07:46:56,019 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: Deleted blk_5292612097544035620_1384 at file /app/hadoop/data/dn/current/blk_5292612097544035620
2014-05-15 07:46:56,019 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: Deleted blk_5318982235915332439_1333 at file /app/hadoop/data/dn/current/blk_5318982235915332439
2014-05-15 07:46:56,019 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: Deleted blk_5806860765395122737_1388 at file /app/hadoop/data/dn/current/blk_5806860765395122737
2014-05-15 07:46:56,019 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: Deleted blk_6490571696460682483_1302 at file /app/hadoop/data/dn/current/blk_6490571696460682483
2014-05-15 07:46:56,020 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: Deleted blk_7721528058087862562_1336 at file /app/hadoop/data/dn/current/blk_7721528058087862562
2014-05-15 07:46:56,020 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: Deleted blk_7734832800955956873_1375 at file /app/hadoop/data/dn/current/blk_7734832800955956873
2014-05-15 07:46:56,020 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: Deleted blk_8691928504867292802_1297 at file /app/hadoop/data/dn/current/blk_8691928504867292802
2014-05-15 07:46:56,020 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: Deleted blk_8861743153245195509_1303 at file /app/hadoop/data/dn/current/blk_8861743153245195509
2014-05-15 07:46:56,021 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: Deleted blk_8921828525927242630_1300 at file /app/hadoop/data/dn/current/blk_8921828525927242630
2014-05-15 07:46:56,021 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: Deleted blk_8938258584084219299_1344 at file

Answer 1

我的问题如下

当我将namenode的新VERSION更改为所有datanode时。并启动datanodes，所有上传的RDBMS数据都被删除，日志文件中出现以下错误“已删除blk_6490571696460682483_1302 at file / app / hadoop / data / dn / current / blk_6490571696460682483”

我的问题是，当我们使用Haddop fs -format命令时，所有数据格式化，是否有恢复数据的方法

namenode -format删除hdfs中的文件

1 个答案: