Moving Hadoop Namenode out of safemode.

Hi There, people has been asking me to put some light on safemode of Hadoop. So lets see what is it.

Many time when you start Hadoop, it gets stuck in Safemode. Now what exactly is this safemode? when Hadoop starts, Normally it puts itself in Safemode. In this mode, you cannot write any new data to hadoop. it is a read only mode. Hadoop says untill  i am going to get heartbeat from some fix number of datanodes, i will keep myself in Safemode. I have seen this happening even when you are in Pseudo distributed mode.
So if your Hadoop is in safemode. you will not be able to write any new data or create any folder on Hadoop. So you have to bring Hadoop out of safemode.

Following is the command for bringing hadoop out of safemode.

      hadoop dfsadmin -safemode leave

After this, you will be able to use Hadoop as normal. Enjoy, Keep Coding, keep facing issues, keep learning :)

Comments

  1. Gaurav Swaroop3 July 2014 at 04:12

    Hi Harijeet,

    Could u plz write something on custom input format??
    Thanks in advance.

    ReplyDelete

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