Open Stack

On 12/4/18 2:15 PM, Thierry Carrez wrote:
> Not sure that is what you're looking for, but the concept of an oslo.db 
> interface to a key-value store was explored by a research team and the 
> FEMDC WG (Fog/Edge/Massively-distributed Clouds), in the context of 
> distributing Nova data around. Their ROME oslo.db driver PoC was using 
> Redis, but I think it could be adapted to use etcd quite easily.
> 
> Some pointers:
> 
> https://github.com/beyondtheclouds/rome
> 
> https://www.openstack.org/videos/austin-2016/a-ring-to-rule-them-all-revising-openstack-internals-to-operate-massively-distributed-clouds

That's interesting, thank you! I'd like to remind though that Edge/Fog 
cases assume high latency, which is not the best fit for strongly 
consistent oslo.db data backends, like Etcd or Galera. Technically, it 
had been proved in the past a few years that only causal consistency, 
which is like eventual consistency but works much better for end users 
[0], is a way to go for Edge clouds. Except that there is *yet* a decent 
implementation exists of a causal consistent KVS!

So my take is, if we'd ever want to redesign ORM transactions et al to 
CAS operations and KVS, it should be done not for Etcd in mind, but a 
future causal consistent solution.

[0] 
https://www.usenix.org/system/files/login/articles/08_lloyd_41-43_online.pdf

-- 
Best regards,
Bogdan Dobrelya,
Irc #bogdando