openstack team mailing list archive

[Vishvananda Ishaya <vishvananda@xxxxxxxxx>]

Hello Everyone,

Now that the PPB has decided to promote Cinder to core for the Folsom
release, we need to decide what happens to the existing Nova Volume
code. As far as I can see it there are two basic strategies. I'm going
to give an overview of each here:

Option 1 -- Remove Nova Volume
==============================

Process
-------
 * Remove all nova-volume code from the nova project
 * Leave the existing nova-volume database upgrades and tables in
   place for Folsom to allow for migration
 * Provide a simple script in cinder to copy data from the nova
   database to the cinder database (The schema for the tables in
   cinder are equivalent to the current nova tables)
 * Work with package maintainers to provide a package based upgrade
   from nova-volume packages to cinder packages
 * Remove the db tables immediately after Folsom

Disadvantages
-------------
 * Forces deployments to go through the process of migrating to cinder
   if they want to use volumes in the Folsom release

Option 2 -- Deprecate Nova Volume
=================================

Process
-------
 * Mark the nova-volume code deprecated but leave it in the project
   for the folsom release
 * Provide a migration path at folsom
 * Backport bugfixes to nova-volume throughout the G-cycle
 * Provide a second migration path at G
 * Package maintainers can decide when to migrate to cinder

Disadvantages
-------------
 * Extra maintenance effort
 * More confusion about storage in openstack
 * More complicated upgrade paths need to be supported

Personally I think Option 1 is a much more manageable strategy because
the volume code doesn't get a whole lot of attention. I want to keep
things simple and clean with one deployment strategy. My opinion is that
if we choose option 2 we will be sacrificing significant feature
development in G in order to continue to maintain nova-volume for another
release.

But we really need to know if this is going to cause major pain to existing
deployments out there. If it causes a bad experience for deployers we
need to take our medicine and go with option 2. Keep in mind that it
shouldn't make any difference to end users whether cinder or nova-volume
is being used. The current nova-client can use either one.

Vish