> volumes.

A `copy_up` operation can incur a noticeable performance overhead. This overhead
is different depending on which storage driver is in use. Large files,
lots of layers, and deep directory trees can make the impact more noticeable.
This is mitigated by the fact that each `copy_up` operation only occurs the first
time a given file is modified.

To verify the way that copy-on-write works, the following procedure spins up 5
containers based on the `acme/my-final-image:1.0` image we built earlier and
examines how much room they take up.

1. From a terminal on your Docker host, run the following `docker run` commands.
   The strings at the end are the IDs of each container.

   ```console
   $ docker run -dit --name my_container_1 acme/my-final-image:1.0 bash \
     && docker run -dit --name my_container_2 acme/my-final-image:1.0 bash \
     && docker run -dit --name my_container_3 acme/my-final-image:1.0 bash \
     && docker run -dit --name my_container_4 acme/my-final-image:1.0 bash \
     && docker run -dit --name my_container_5 acme/my-final-image:1.0 bash

   40ebdd7634162eb42bdb1ba76a395095527e9c0aa40348e6c325bd0aa289423c
   a5ff32e2b551168b9498870faf16c9cd0af820edf8a5c157f7b80da59d01a107
   3ed3c1a10430e09f253704116965b01ca920202d52f3bf381fbb833b8ae356bc
   939b3bf9e7ece24bcffec57d974c939da2bdcc6a5077b5459c897c1e2fa37a39
   cddae31c314fbab3f7eabeb9b26733838187abc9a2ed53f97bd5b04cd7984a5a
   ```

2. Run the `docker ps` command with the `--size` option to verify the 5 containers
   are running, and to see each container's size.

   
   ```console
   $ docker ps --size --format "table {{.ID}}\t{{.Image}}\t{{.Names}}\t{{.Size}}"

   CONTAINER ID   IMAGE                     NAMES            SIZE
   cddae31c314f   acme/my-final-image:1.0   my_container_5   0B (virtual 7.75MB)
   939b3bf9e7ec   acme/my-final-image:1.0   my_container_4   0B (virtual 7.75MB)
   3ed3c1a10430   acme/my-final-image:1.0   my_container_3   0B (virtual 7.75MB)
   a5ff32e2b551   acme/my-final-image:1.0   my_container_2   0B (virtual 7.75MB)
   40ebdd763416   acme/my-final-image:1.0   my_container_1   0B (virtual 7.75MB)
   ```
   
   The output above shows that all containers share the image's read-only layers
   (7.75MB), but no data was written to the container's filesystem, so no additional
   storage is used for the containers.

   {{< accordion title="Advanced: metadata and logs storage used for containers" >}}
   
   > [!NOTE]
   >
   > This step requires a Linux machine, and doesn't work on Docker Desktop, as
   > it requires access to the Docker Daemon's file storage.
   
   While the output of `docker ps` provides you information about disk space
   consumed by a container's writable layer, it doesn't include information
   about metadata and log-files stored for each container.
   
   More details can be obtained by exploring the Docker Daemon's storage