I'm trying to figure out some details of Openstack behaviour with respect to ephemeral disks. I have found some information in the Operations Guide under the 'Flavors' and 'Storage' sections as well as some little bits in the End Users Guide and wiki. I see that the size of the ephemeral disk for an instance is specified in the flavour for the instance. I have the following questions: When launching an instance will the instance automatically get as much ephemeral storage as specified by the ‘Ephemeral’ parameter of the flavour without any further explicit input from the user at launch time? One place in the docs mentions that the user can specify ephemeral disks at launch time, but the amount shouldn’t exceed the ephemeral size specified by the flavour. This suggests the instance will not get ephemeral disks unless the user specifies this at launch. However the devstack launch instance wizard in the web GUI doesn’t offer a place to input ephemeral storage specs. Can anyone clarify the different ways in which ephemeral storage can be specified for an instance?