[openstack-dev] [Nova] Preserving ephemeral block device on rebuild?

Robert Collins robertc at robertcollins.net
Mon Oct 28 19:28:02 UTC 2013


On 29 October 2013 02:35, John Griffith <john.griffith at solidfire.com> wrote:

> Personally I'd rather go the proper route and try to get what you need in to
> Cinder, FWIW the local storage provisioning is something that Vish brought

We -totally- want to do that but it's not the same as local storage :
remember that we have /no hypervisor/ - there is nowhere for a cinder
backend to run in baremetal. All of the actual execution / allocation
/ management has to be split between the deploy ramdisk (size limited)
and the baremetal compute's deploy-helper process which operates over
iscsi. We have to make sure we can schedule properly, and have volume
creation happen before provisioning, but still land on the right
physical machine; we need to stop allowing instance allocation to
physical machines with different volumes on them...

it's a tonne of work - very valuable, and we will *totally* get to it,
but not at all suitable for doing in nova-bm - thats deprecated for
major development now.

Having /something/ in place is super valuable to us, as it allows us
to move forward in parallel on both the actual TripleO story, and the
evolution of Ironic into a super capable bare metal 'hypervisor'.

> up last summit but nobody picked it up.  I'd like to make that happen early
> in I.  I'm not familiar with the work-around your proposing though so maybe
> it's not an issue, just hate to put in a temporary hack that will end up
> likely taking on a life of its own once it lands.

Taking a life of it's own is a good point. I like the thing we came up
with - the proposal in this thread - because I think it's generally
useful. It's true that a local Cinder provider would give the same
benefits for users, so perhaps the ephemeral change I'm talking about
should be an extension, off by default, so that it's easier to sunset
it when Cinder local provider comes about?

-Rob

-- 
Robert Collins <rbtcollins at hp.com>
Distinguished Technologist
HP Converged Cloud



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