namenode -format delete files in hdfs

Question

I uploaded data successfully from mysql to HDFS by sqoop command.

MySQL Hadoop Cluster have

1 Node for Namename 1 Node for Secondary NameNode 1 Node for Jobtracker 3 Nodes for Datanade + Tasktracker

After that I stopped the hadoop cluster.

And again to start Hadoop

Used below command

  namenode -format (start NameNode)

  place new VERSION number in all datanode VERSION FILE

  now START DATANODE 

While starting datanode my upload MYSQL Data in HDFS seems to be lost.

Below is the output from the datanode logs.

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

My Question as below

When I changed new VERSION of namenode to all datanode . and started datanodes , all uploaded RDBMS data is deleted with below error in log file "Deleted blk_6490571696460682483_1302 at file /app/hadoop/data/dn/current/blk_6490571696460682483"

My Question is when we use Haddop fs -format command is all data formatted , Is there way to recover data