MapReduce Filesystem Recovery

Administration Lab 5:  MapReduce Filesystem Recovery

Restore the Last State of VM

    Open Virtual Box application

    Start the last VM state

    Stop Hadoop cluster

for x in /etc/init.d/hadoop-* ; do sudo $x stop; done

Procedure to Recover Namenode

    Change user to hdfs

sudo su hdfs

    Lets try to import image

hadoop-0.20 namenode –importCheckpoint

    This will fail!!! (Why???)

    Lets move data to home directory

mkdir ~/name

mv /var/lib/hadoop-0.20/cache/hadoop/dfs/name/* ~/name

ls /var/lib/hadoop-0.20/cache/hadoop/dfs/name

    Lets try import again

hadoop-0.20 namenode –importCheckpoint

    This will work!

    Ctrl-C to terminate node and exit from shell

    Start the cluster

for x in /etc/init.d/hadoop-* ; do sudo $x start; done

Checking Filesystem

hadoop-0.20 fsck <file name> -files -blocks -racks