title: How to free up space on docker devmapper and CentOS7?
body: <p>I am learning docker and I am using v1.11.0
  I am trying to install hadoop but devmapper is complaining about free disk space?</p>
  <pre><code>devmapper: Thin Pool has 82984 free data blocks which is less than minimum required 163840 free data blocks. Create more free space in thin pool or use dm.min_free_space option to change behavior
  </code></pre>
  <p>I have deleted all my images but the problem persists:</p>
  <pre><code>[root@localhost hadoop_docker]# docker images
  REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
  debian              latest              47af6ca8a14a        3 weeks ago         125 MB
  [root@localhost hadoop_docker]#
  </code></pre>
  <p>and this is my disk configuration:</p>
  <pre><code>[root@localhost ~]# lsblk
  NAME                       MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
  sda                          8:0    0    8G  0 disk
  ├─sda1                       8:1    0  500M  0 part /boot
  └─sda2                       8:2    0  7.5G  0 part
    ├─centos-root            253:0    0  6.7G  0 lvm  /
    └─centos-swap            253:1    0  820M  0 lvm  [SWAP]
  sr0                         11:0    1 1024M  0 rom
  loop0                        7:0    0  100G  0 loop
  └─docker-253:0-844682-pool 253:2    0  100G  0 dm
  loop1                        7:1    0    2G  0 loop
  └─docker-253:0-844682-pool 253:2    0  100G  0 dm
  </code></pre>
  <p>How can I free up the disk space?</p>