openstack team mailing list archive

[John Griffith <john.griffith@xxxxxxxxxxxxx>]

Hi Everyone,

Throughout the email thread regarding how to proceed with
cinder/nova-volumes and a number of IRC conversations I thought I
should try and clarify a few things about Cinder.

First, it should be clear that Cinder is literally a direct copy of
the existing nova-volume code.  This was intentional in order to
maintain compatibility and provide a 'sane' transition.  The goal for
Folsom from the very start was clearly stated as providing a
functional equivalent and as near compatible version as possible (I
won't say 100% because there's always room for interpretation with
regard to what compatibility means).  There are a number of things
that were considered and done to make things better for the community:

1. For the most part it's the same code
2. The usage semantics are the same
3. You can still use novaclient just as you did before
4. You can use euca2ools to the same extent that you did before
5. You can also use the new cinderclient

The only thing we're really changing at this point is that now the
volume service is it's own project.  This of course means that there
is some up front configuration regarding a different end point etc,
but that really is the bulk of it.  You'll notice for example that all
of the existing devstack tests etc work exactly the same with cinder
as they do with nova-volume, we're not suggesting anybody replace
nova-volume with an incompatible interface.

I want to be very clear that myself and just about everybody else I've
talked with and worked with DO in fact care about compatibility as
well as customer impacts.  I know one concern is migration, that's
something that is critical and if Cinder doesn't have a robust and
clean migration mechanism in place by F3 I don't think we would ask
anybody to switch from what they already have.

Thanks,
John