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From Rene Moser <m...@renemoser.net>
Subject Re: [DISCUSS] VR upgrade downtime reduction
Date Wed, 07 Feb 2018 10:11:45 GMT
On 02/06/2018 02:47 PM, Remi Bergsma wrote:
> Hi Daan,
> 
> In my opinion the biggest issue is the fact that there are a lot of different code paths:
VPC versus non-VPC, VPC versus redundant-VPC, etc. That's why you cannot simply switch from
a single VPC to a redundant VPC for example. 
> 
> For SBP, we mitigated that in Cosmic by converting all non-VPCs to a VPC with a single
tier and made sure all features are supported. Next we merged the single and redundant VPC
code paths. The idea here is that redundancy or not should only be a difference in the number
of routers. Code should be the same. A single router, is also "master" but there just is no
"backup".
> 
> That simplifies things A LOT, as keepalived is now the master of the whole thing. No
more assigning ip addresses in Python, but leave that to keepalived instead. Lots of code
deleted. Easier to maintain, way more stable. We just released Cosmic 6 that has this feature
and are now rolling it out in production. Looking good so far. This change unlocks a lot of
possibilities, like live upgrading from a single VPC to a redundant one (and back). In the
end, if the redundant VPC is rock solid, you most likely don't even want single VPCs any more.
But that will come.
> 
> As I said, we're rolling this out as we speak. In a few weeks when everything is upgraded
I can share what we learned and how well it works. CloudStack could use a similar approach.

+1 Pretty much this.

René

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