Cloned from launchpad blueprint https://blueprints.launchpad.net/nova/+spec/select-caching-method-while-attaching-a-device.

Description:

 At some point and depending on your application using the block device, you would like to be able to either specify none, writethrough, writeback caching options. This is currently possible in OpenStack, however this will affect all the attached volumes, there is no way to specify the option for a specific volume. Eventually, the user will be able to decide which caching method is the most suitable for his device.

This needs a new API function and new option in the CLI:

nova attach-volume --caching-method writeback <server> <volume> <device>

Specification URL (additional information):

None