[openstack-dev] [nova][cinder] Rocky PTG summary - nova/cinder

melanie witt melwittt at gmail.com
Thu Mar 15 20:42:43 UTC 2018

I realized I forgot to add the [cinder] tag to the subject line when I 
sent this originally. Sorry about that.

Hello all,

Here’s the PTG summary etherpad [0] for the nova/cinder session from the 
PTG, also included as a plain text export on this email.


[0] https://etherpad.openstack.org/p/nova-ptg-rocky-cinder-summary

*Nova/Cinder: Rocky PTG Summary

https://etherpad.openstack.org/p/nova-ptg-rocky L63

*Key topics

   * New attach flow fixes and multi-attach
     * Attach mode
     * Swap volume with two read/write attachments
     * SHELVED_OFFLOADED and 'in-use' state in old attach flow
     * Server multi-create with attaching to the same volume fails
   * Data migration for old-style attachments
   * Volume replication for in-use volumes
   * Object-ifying os-brick connection_info
   * Formatting blank encrypted volumes during creation on the cinder side
   * Volume detail show reveals the attached compute hostname for non-admins
   * Bulk volume create/attach

*Agreements and decisions

   * To handle attach mode for a multi-attach volume to several 
instances, we will change the compute API to allow the user to pass the 
attach mode so we can pass it through to cinder
     * The second attachment is going to be read/write by default and if 
the user wants read-only, they have to specify it
     * Spec: https://review.openstack.org/#/c/552078/
   * Swap volume with two read/write attachments could definitely 
corrupt data. However, the cinder API doesn't allow retype/migration of 
in-use multi-attach volumes, so this isn't a problem right now
   * It would be reasonable to fix SHELVED_OFFLOADED to leave the volume 
in 'reserved' state instead of 'in-use', but it's low priority
   * The bug with server multi-create and multi-attach will be fixed on 
the cinder side and we'll add a new compute API microversion to leverage 
the cinder fix
     * Spec: https://review.openstack.org/#/c/552078/
   * We'll migrate old-style attachments on-the-fly when a change is 
made to a volume, such as a migration. For the rest, we'll migrate 
old-style attachments on compute startup to new-style attachments
     * Compute startup data migration patch: 
   * For volume replication of in-use volumes, on the cinder side, we'll 
need a prototype and spec, and drivers will need to indicate the type of 
replication and what recovery on the nova side needs to be. On the nova 
side, we'll need a new API microversion for the 
os-server-external-events change (like extended volume)
     * Owner: jgriffith
   * On the possibility of object-ifying connection_info in os-brick, it 
would be best to defer it until nova/neutron have worked out vif 
negotiation using os-vif
     * lyarwood asked to restore https://review.openstack.org/#/c/269867/
   * On formatting blank encrypted volumes during creation, it sounded 
like we had agreement to fix it on the cinder side as they already have 
code for it. Need to double-check with the cinder team to make sure
   * For volume detail show revealing the attached compute hostname for 
non-admins, cinder will make a change to add a policy to not display the 
compute hostname for non-admins
     * Note: this doesn't impact nova, but it might impact glance.
   * On bulk volume create/attach, it will be up to cinder to decide 
whether they will want to implement bulk create. In nova, we are not 
going to support bulk attach as that's a job better done by an 
orchestration system like Heat
     * Note: Cinder team agreed to not support bulk create: 

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