Machine: How to set the dynamic image size for docker-machine create

@duynguyenvan - Run docker-machine create --help, it will show you all the available options. In this case, you could use the --virtualbox-disk-size option. Example setting the disk to 2GB:

$ docker-machine create --virtualbox-disk-size 2000 -d virtualbox dev -D

Output you referenced:

STDERR: 
Image cache does not exist, creating it at /Users/brint/.docker/machine/cache...
No default boot2docker iso found locally, downloading the latest release...
Downloading https://github.com/boot2docker/boot2docker/releases/download/v1.7.1/boot2docker.iso to /Users/brint/.docker/machine/cache/boot2docker.iso...
Creating VirtualBox VM...
Creating SSH key...
Creating disk image...
Creating 2000 MB hard disk image...
Converting from raw image file="stdin" to file="/Users/brint/.docker/machine/machines/dev/disk.vmdk"...
Creating dynamic image with size 2097152000 bytes (2000MB)...

You'll see that it only allocated 2,000MB as opposed to the default 20,000MB.

Thanks @brint. You can also refer to http://docs.docker.com/machine/reference/create/ for details on create`.

Thanks @brint and @ehazlett. I can change the image size now. Unfortunately the problem is still there as shown in the log below. Any idea please?
STDERR:
Creating VirtualBox VM...
Creating SSH key...
Creating disk image...
Creating 2000 MB hard disk image...
Converting from raw image file="stdin" to file="/root/.docker/machine/machines/dev/disk.vmdk"...
Creating dynamic image with size 2097152000 bytes (2000MB)...
executing: /usr/bin/VBoxManage createvm --basefolder /root/.docker/machine/machines/dev --name dev --register
STDOUT:
STDERR: VBoxManage: error: Failed to create the VirtualBox object!
VBoxManage: error: Code NS_ERROR_ABORT (0x80004004) - Operation aborted (extended info not available)
VBoxManage: error: Most likely, the VirtualBox COM server is not running or failed to start.

Error creating machine: exit status 1
You will want to check the provider to make sure the machine and associated resources were properly removed.