[openstack-dev] Upgrade skip release

Matt Riedemann mriedem at linux.vnet.ibm.com
Tue Dec 20 02:29:12 UTC 2016

On 12/19/2016 4:26 PM, Chris Friesen wrote:
> On 12/19/2016 03:17 PM, Ajay Kalambur (akalambu) wrote:
>> Hi Chris
>> Thanks for the response. What were the specific problem areas you saw
>> when upgrading from Kilo to Mitaka which were introduced by skipping
>> Liberty?
> There were issues with RPC incompatibility, object versioning, DB
> upgrades, etc.
> Liberty had compatibility code for this stuff, but then it got ripped
> out early in Mitaka since it was assumed to be no longer needed.
> Chris
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Right, it's not only about database schema migrations anymore, which in 
the before times you could generally just roll those forward and skip a 

Nova has been doing online data migrations since Kilo, and assumptions 
are made that you're doing lock-step N to N+1 upgrades and running the 
schema and online data migrations, and rolling services forward in that 
fashion so that we can drop compatibility code after a full release of 
that compat code being in place.

We only test N to N+1 in the CI system (the grenade jobs) so while 
things might work in practice by skipping a release, it's not tested 
that way upstream at all so any chance of it working is accidental and 
shouldn't be relied upon or really expected to be supported that way 



Matt Riedemann

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