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In the live migration meeting today mdbooth and I were chatting about 
how hard it is to follow the various BDM code through nova, because you 
have the three block_device modules:

* nova.block_device - dict that does some translation magic
* nova.objects.block_device - contains the BDM(List) objects for RPC and 
DB access
* nova.virt.block_device - dict that wraps a BDM object, used for 
attaching volumes to instances, updates the BDM.connection_info field in 
the DB via the wrapper on the BDM object. This module also has 
translation logic in it.

The BDM v1 extension translates that type of request to the BDM v2 model 
before it gets to server create, and then passed down to the 
nova.compute.api. But there is still a lot of legacy bdm v1 translation 
logic spread through the code.

So I'd like to propose that we deprecate the v1 BDM API in the same vein 
that we're deprecating other untested things, like agent-builds, 
cloudpipe, certificates, and the proxy APIs. We can't remove the code, 
but we can signal to users to not use the API and eventually when we 
raise the minimum required microversion >= the deprecation, we can drop 
that code. Since that's a long ways off, the earlier we start a 
deprecation clock on this the better - if we're going to do it.

Does anyone have any issues with this?

-- 

Thanks,

Matt Riedemann