Add disk for datanode in CDH4

First step: add the disk, make the partition, mount to the machine

• connect HDD to machine

• ls /dev/[sh]d*

  The one not ending with a number should be the new HDD, e.g. /dev/sdb
• create partition on the new disk (assume create one partition on the entire disk)

  fdisk /dev/sdb
  => command n   add a new partition
  => select primary
  => default partition number 1
  => default start cylinder
  => default end cylinder
  => command w   write table to disk and exit
  => command q leave fdisk

• list partitions on the new disk

  fdisk -l /dev/sdb

  you should see /dev/sdb1
• format the partition

  mkfs -t ext4 /dev/sdb1

• get the UUID of disk

  blkid

  copy the UUID, assume it's a-b-c-d-e
• mount the partition, assume we're trying to mount on /data2
  add the line to file </etc/fstab>

  UUID=a-b-c-d-e /data2 ext4 defaults 0

• reboot
• mount /data2

Step 2: change the attributes of the folder

This step is very important!

chgrp hadoop /data2
chown hdfs /data2

Step 3: add this folder to datanode setting by CDH Manager

Step 4: restart HDFS

check out the space now by namenode's status page: http://xxxx:50070/dfshealth.jsp