Understanding Instances and Block Volumes attached to it.
I am new to OpenStack and and I'm confused about where an instance is launched and if I want to attach a volume to that instance how will I go about doing that.
According to my understanding an Instance is launched on the compute, using the computes storage. if we want to attach a volume to that instance we will first create a volume through horizon or cinder and run the nova attach-volume <server id> <volume id>
command from the controller.
So, First my question is am I right in this understanding. Second can I simply add a storage to the compute through SAN or NAS and directly attach it with the instance bypassing the controller?
Any guidance in this would be greatly appreciated.