Cinder

OpenStack Block Storage ("Cinder")

The goal of the Cinder project is to separate the existing nova-volume block service into its own project.

Reasoning:

1. Nova is currently a very large project; managing all of the dependencies in linkages of services within Nova can make the ability to advance new features and functionality very difficult.
2. As a result of the many components and dependencies in Nova, it's difficult for anybody to really have a complete view of Nova and to be a true expert. This makes the job of core team member on Nova very difficult, and inhibits good thorough reviews of bug and blueprint submissions.
3. Block storage is a critical component of OpenStack, as such it warrants focused and dedicated attention.
4. Having Block Storage as a dedicated core project in OpenStack enables the ability to greatly improve functionality and reliability of the block storage component of OpenStack

Goals for Folsom release:

• Provide as close to a "drop in" replacement/alternative to nova-volume
• Emphasis on limiting disruption
• * Operate using the same novaclient commands that are used today (nova volume-create, nova volume-snapshot-create, etc)
• * Utilize the same architecture and code, just separate it out of the Nova project
• * Cinder is LITERALLY a copy and paste of the nova-volume code

Keeping informed and providing CONSTRUCTIVE INPUT

The Cinder team currently meets on a weekly basis in #openstack-meeting at 16:00 UTC on Wednesdays. I try to keep the meetings wiki agenda page http://wiki.openstack.org/NovaVolumeMeetings up to date and follow it. Also keep in mind that anybody is able to add/suggest agenda items via the meeting wiki page.

Of course, there's also IRC... a number of us monitor #openstack-cinder or you can always send a PM to jgriffith (that's me)http://wiki.openstack.org/NovaVolumeMeetings

Concerns from the community:

Compatibility and Migration:

There has been a significant amount of concern raised regarding "compatibility"; unfortunately this seems to mean different things to different people. For those that haven't looked at the Cinder code or tried a demo in devstack, here are some question/answers:

• Do the same nova client commands I use for volumes today still work the same? YES
• Do the same euca2ools that I use for volumes today still work the same? YES
• Does block storage still work the same as it does today in terms of LVM, iSCSI and the drivers that are curently in place? YES
• Are the associated database tables the same as they are in the current nova volume code? For the most part YES, all volume related tables and columns are migrated, non-volume related tables however are not present
• Does it use the same nova database as we use today? No, it does require a new independent database
• Are you going to implement cinder with complete disregard for my current install and completely change everything out from under me? ABSOLUTELY NOT
• Are you going to test migrating from nova-vol to Cinder? YES
• Are those migration tests going to be done just using fakes/unit tests? NO, we would require running setups, most likely devstack
• Are you planning to provide migration scripts/tools to move from nova to cinder? YES

Additional thoughts to keep in mind:

• The Cinder core team is fortunate enough to have a number of members who currently work for companies that are using OpenStack and nova-volumes in production environments. There is a strong representation and the concerns of Providers is in fact a major consideration
• The goal is NOT to throw away nova-volume as it is today, but to separate it, focus on it and improve it.
• Migration is one of the top priorities for introduction of Cinder into Folsom (regardless of whether nova-volume is still in place or not). This is something that is just considered a part of the requirements for the project.