Hello, We're running a cluster with 12 DataNode servers, each has 12 physical disks mounted as follows: /dev/sda5 on /grid/0 type ext4 (rw,noatime) /dev/sdb1 on /grid/1 type ext4 (rw,noatime) /dev/sdc1 on /grid/2 type ext4 (rw,noatime) /dev/sdd1 on /grid/3 type ext4 (rw,noatime) /dev/sde1 on /grid/4 type ext4 (rw,noatime) /dev/sdf1 on /grid/5 type ext4 (rw,noatime) /dev/sdg1 on /grid/6 type ext4 (rw,noatime) /dev/sdh1 on /grid/7 type ext4 (rw,noatime) /dev/sdi1 on /grid/8 type ext4 (rw,noatime) /dev/sdj1 on /grid/9 type ext4 (rw,noatime) /dev/sdk1 on /grid/10 type ext4 (rw,noatime) /dev/sdl1 on /grid/11 type ext4 (rw,noatime) We've tried adding 5 newly deployed DataNodes which are stronger and greater by all means (capacity, cpu & ram) to the cluster with the following disk layout: /dev/sda1 on /grid/0 type ext4 (rw,noatime) /dev/sdb1 on /grid/1 type ext4 (rw,noatime) /dev/sdc1 on /grid/2 type ext4 (rw,noatime) /dev/sdd1 on /grid/3 type ext4 (rw,noatime) /dev/sde1 on /grid/4 type ext4 (rw,noatime) /dev/sdf1 on /grid/5 type ext4 (rw,noatime) /dev/sdg1 on /grid/6 type ext4 (rw,noatime) /dev/sdh1 on /grid/7 type ext4 (rw,noatime) /dev/sdi1 on /grid/8 type ext4 (rw,noatime) /dev/sdj1 on /grid/9 type ext4 (rw,noatime) /dev/sdk1 on /grid/10 type ext4 (rw,noatime) /dev/sdl1 on /grid/11 type ext4 (rw,noatime) /dev/sdm1 on /grid/12 type ext4 (rw,noatime) /dev/sdn1 on /grid/13 type ext4 (rw,noatime) /dev/sdo1 on /grid/14 type ext4 (rw,noatime) /dev/sdp1 on /grid/15 type ext4 (rw,noatime) New DataNodes have 4 disks extra so we added /grid/12/hadoop/hdfs/data, /grid/13/hadoop/hdfs/data, /grid/14/hadoop/hdfs/data, /grid/15/hadoop/hdfs/data to DataNode directories in HDFS config. Everywhere we searched, was written that in case directories does not exist, they will be ignored (because previous DataNodes lacks /grid/12,13,14,15 mount points). What actually happened is, on previous DataNodes under /grid folders (12/,13/,14/,15/) were created and are filling up with HDFS data. Since they are mounted on / (and not on a dedicated block device), space is about to run out which is probably, not a good thing. How to proceed now? How to remove the data which landed there to free root (/) partition space? Thanks, ... View more