Create a dummy file of specified size

If you need to create a big file of specified size for testing purposes (for testing Glance or Cinder for example), you can follow next few steps:

• Install fallocate tool from util-linux
  $ sudo apt-get install util-linux
• Create your dummy file of specified size. Let's do a file of 1Gb size
  $ fallocate -l 1G dummy.iso

Then you can use it, for example upload to Glance:

$ glance image-create --name dummy.iso --disk-format iso --container-format bare --file dummy.iso