title: Why the virtual size still the same after delete a file from container with rm?
body: <p>I would like to know more about Docker. I'm so beginner, very new with this and linux.
  My English is not perfect therefore I copied the Terminal output.
  I had an image with 516MB VIRTUAL SIZE.
  I started the bash in a container and i use wget to download some 26MB data into this. After the downloading I create a image from the container's changes with commit. After that the VIRTUAL SIZE was 542.5MB. That is correct.
  After the commit I started again the bash, and I deleted this file.
  When i committed the changes the image VIRTUAL SIZE was 542.8MB. </p>
  
  <p>This size does not decreased, instead increased.
  Could you tell me the reason?</p>
  
  <p>Local images:
  </p>
  
  <pre><code>[fedora_user@fedora-vm ~]$ docker images
  REPOSITORY             TAG                 IMAGE ID            CREATED             VIRTUAL SIZE
  tester/mytestfedora   latest              c0ca83567bdd        4 seconds ago       516 MB
  fedora                 latest              834629358fe2        3 months ago        241.3 MB
  </code></pre>
  
  <p>Using the smallest one and downloading a file:
  </p>
  
  <pre><code>[fedora_user@fedora-vm ~]$ docker run -i -t tester/mytestfedora /bin/bash
  bash-4.3# su dockeres
  [dockeres@05ef6e284e32 /]$ cd /home/dockeres/downloads/    
  [dockeres@05ef6e284e32 downloads]$ wget https://dl.dropboxusercontent.com/u/827503/0_TEMP/Riverbed.zip
  --2015-03-31 19:24:47--  https://dl.dropboxusercontent.com/u/827503/0_TEMP/Riverbed.zip
  Resolving dl.dropboxusercontent.com (dl.dropboxusercontent.com)... 54.243.97.104, 54.243.80.193, 50.16.185.28, ...
  Connecting to dl.dropboxusercontent.com (dl.dropboxusercontent.com)|54.243.97.104|:443... connected.
  HTTP request sent, awaiting response... 200 OK
  Length: 26177252 (25M) [application/zip]
  Saving to: 'Riverbed.zip'
  Riverbed.zip                      100%[==============================================================&gt;]  24.96M  3.66MB/s   in 14s    
  2015-03-31 19:25:03 (1.78 MB/s) - 'Riverbed.zip' saved [26177252/26177252]
  [dockeres@05ef6e284e32 downloads]$ exit
  bash-4.3# exit
  </code></pre>
  
  <p>List the active ones and create a new image from a container's changes:
  </p>
  
  <pre><code>[fedora_user@fedora-vm ~]$ docker ps -all
  CONTAINER ID        IMAGE                         COMMAND             CREATED             STATUS                     PORTS               NAMES
  05ef6e284e32        tester/mytestfedora:latest   "/bin/bash"         2 minutes ago       Exited (0) 6 seconds ago                       sick_einstein       
  [fedora_user@fedora-vm ~]$ docker commit 05ef6e284e32 tester/mytestfedora
  f122b12e94a32d477f2f2f18c5a5190a9ad5d349109933da65a0cfeff448c822
  [fedora_user@fedora-vm ~]$ docker images
  REPOSITORY             TAG                 IMAGE ID            CREATED             VIRTUAL SIZE
  tester/mytestfedora   latest              f122b12e94a3        5 seconds ago       542.5 MB
  fedora                 latest              834629358fe2        3 months ago        241.3 MB
  </code></pre>
  
  <p>Access it again and remove the downloaded file:
  </p>
  
  <pre><code>[fedora_user@fedora-vm ~]$ docker run -i -t tester/mytestfedora /bin/bash
  [dockeres@fb5ba36692f0 /]$ cd /home/dockeres/downloads/             
  [dockeres@fb5ba36692f0 downloads]$ rm -f Riverbed.zip              
  [dockeres@fb5ba36692f0 downloads]$ ls
  [dockeres@fb5ba36692f0 downloads]$ exit
  bash-4.3# exit
  </code></pre>
  
  <p>List the active ones again and create a new image from a container's changes:
  </p>
  
  <pre><code>[fedora_user@fedora-vm ~]$ docker ps -all
  CONTAINER ID        IMAGE                         COMMAND             CREATED             STATUS                     PORTS               NAMES
  fb5ba36692f0        tester/mytestfedora:latest   "/bin/bash"         51 seconds ago      Exited (0) 5 seconds ago                       goofy_yalow         
  [fedora_user@fedora-vm ~]$ docker commit fb5ba36692f0 tester/mytestfedora
  f744e248576d7fa434768a1e1d25625a9654020fe77e12306f304ff5d5ad3e3b
  [fedora_user@fedora-vm ~]$ docker images
  REPOSITORY             TAG                 IMAGE ID            CREATED             VIRTUAL SIZE
  tester/mytestfedora   latest              f744e248576d        3 seconds ago       542.8 MB
  fedora                 latest              834629358fe2        3 months ago        241.3 MB
  </code></pre>
  
  <p>Thank you in advance for any help you can provide.</p>
  
  <p>Ed</p>