hdfs dfsadmin -metasave

Introduction

hdfs dfsadmin -metasave provides additional information compared to hdfs dfsadmin -report. With hdfs dfsadmin -metasave provides information about blocks, including>

  • blocks waiting for replication
  • blocks currently being replication
  • total number of blocks

hdfs dfsadmin -metasave filename.txt

Run the command with sudo -u hdfs prefixed to ensure you don’t get a permission denied error. CDH4 runs the namenode as the hdfs user by default. However if you have changed the

ssudo -u hdfs hdfs dfsadmin -metasave metasave-report.txt

You will see output similar to:


Created file metasave-report.txt on server hdfs://localhost:8020

The output above initially confused me as I thought the metasave report was saved to the HDFS filesystem. However, it’s stating the the metasave report is saved into the /var/log/hadoop-hdfs directory on localhost.

cd /var/log/hadoop-hdfs
cat metasave-report.txt

You will see output similar to:


58 files and directories, 17 blocks = 75 total
Live Datanodes: 1
Dead Datanodes: 0
Metasave: Blocks waiting for replication: 0
Mis-replicated blocks that have been postponed:
Metasave: Blocks being replicated: 0
Metasave: Blocks 0 waiting deletion from 0 datanodes.
Metasave: Number of datanodes: 1
127.0.0.1:50010 IN 247241674752(230.26 GB) 323584(316 KB) 0% 220983930880(205.81 GB) Sat Jul 14 18:52:49 PDT 2012

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