Thanks Blake ... all very valid points.

Based on our discussions yesterday (the ink is still wet on the whiteboard) 
we've been kicking around numbers in the following ranges:

500-1000 hosts per zone (zone = single nova deployment. 1 db, 1 rabbit)
25-100 instances per host (minimum flavor)
3s api response time fully loaded (over that would be considered a failure). 
'nova list' being the command that can bring down the house. But also 'nova 
boot' is another concern. We're always trying to get more async operations in 

Hosts per zone is a tricky one because we run into so many issues around 
network architecture, so your mileage may vary. Network is the limiting factor 
in this regard.

All of our design decisions are being made with these metrics in mind.

That said, we'd love to get more feedback on realistic metric expectations to 
ensure we're in the right church.

Hope this is what you're looking for?


From: Blake Yeager []
Sent: Thursday, January 26, 2012 12:13 PM
To: Sandy Walsh
Subject: Re: [Openstack] [Scaling][Orchestration] Zone changes. WAS: [Question 
#185840]: Multi-Zone finally working on ESSEX but cant "nova list" (KeyError: 
'uuid') + doubts


I am excited to hear about the work that is going on around communication 
between trusted zones and look forward to seeing what you have created.

In general, the scalability of Nova is an area where I think we need to put 
additional emphasis.  Rackspace has done a lot of work on zones, but they don't 
seem to be receiving a lot of support from the rest of the community.

The OpenStack mission statement indicates the mission of the project is: "To 
produce the ubiquitous Open Source cloud computing platform that will meet the 
needs of public and private cloud providers regardless of size, by being simple 
to implement and massively scalable."

I would challenge the community to ensure that scale is being given the 
appropriate focus in upcoming releases, especially Nova.  Perhaps we need to 
start by setting very specific scale targets for a single Nova zone in terms of 
nodes, instances, volumes, etc.  I did a quick search of the wiki but I didn't 
find anything about scale targets.  Does anyone know if something exists and I 
am just missing it?  Obviously scale will depend a lot on your specific 
hardware and configuration but we could start by saying with this minimum 
hardware spec and this configuration we want to be able to hit this scale.  
Likewise it would be nice to publish some statistics about the scale that we 
believe a given release can operate at safely.  This would tie into some of the 
QA/Testing work that Jay & team are working on.

Does anyone have other thoughts about how we ensure we are all working toward 
building a massively scalable system?


On Thu, Jan 26, 2012 at 9:20 AM, Sandy Walsh 
<<>> wrote:
Zones is going through some radical changes currently.

Specifically, we're planning to use direct Rabbit-to-Rabbit communication 
between trusted Zones to avoid the complication of changes to OS API, Keystone 
and novaclient.

To the user deploying Nova not much will change, there may be a new service to 
deploy (a Zones service), but that would be all. To a developer, the code in OS 
API will greatly simplify and the Distributed Scheduler will be able to focus 
on single zone scheduling (vs doing both zone and host scheduling as it does 

We'll have more details soon, but we aren't planning on introducing the new 
stuff until we have a working replacement in place. The default Essex Scheduler 
now will largely be the same and the filters/weight functions will still carry 
forward, so any investments there won't be lost.

Stay tuned, we're hoping to get all this in a new blueprint soon.

Hope it helps,

[<>] on behalf of Alejandro 
Sent: Thursday, January 26, 2012 8:50 AM
To: Sandy Walsh
Subject: Re: [Question #185840]: Multi-Zone finally working on ESSEX but cant   
"nova list" (KeyError: 'uuid') + doubts

Question #185840 on OpenStack Compute (nova) changed:

   Status: Answered => Open

Alejandro Comisario is still having a problem:
Sandy, Vish !

Thanks for the replies ! let me get to the relevant points.

#1 I totally agree with you guys, the policy for spawning instances
maybe very special of each company strategy, but, as you can pass from
"Fill First" to "Spread First" just adding a "reverse=True" on
nova.scheduler.least_cost.weighted_sum" and
"nova.scheduler.distributed_scheduler._schedule" maybe its a harmless
addition to manipulate (since we are going to have a lot of zones across
datacenters, and many different departments are going to create many
instances to load-balance their applications, we really preffer
SpreadFirst to make sure hight availability of the pools )

#2 As we are going to test essex-3, i would like if you can tell me if
the zones code from Chris Behrens is going to be added on Final Essex /
Milestone 4, so we can keep testing other features, or you preffer us to
load this as a bug to be fixed since maybe the code that broke is not
going to have major changes.

Kindest regards !

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