In HDFS, DataNode supports hot swappable drives. With a swappable drive we can add or replace HDFS data volumes while the DataNode is still running.
The procedure for replacing a hot swappable drive is as follows:
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<li>First we format and mount the new drive.</li> <li>We update the DataNode configuration dfs.datanode.data.dir to reflect the data volume directories.</li> <li>Run the "dfsadmin -reconfig datanode HOST:PORT start" command to start the reconfiguration process</li> <li>Once the reconfiguration is complete, we just unmount the old data volume</li> <li>After unmount we can physically remove the old disks.</li>