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From Nitin Mehta <Nitin.Me...@citrix.com>
Subject Re: [PROPOSAL] [CLOUDSTACK-2056] DeploymentPlanner choice via ServiceOffering
Date Thu, 18 Apr 2013 07:03:40 GMT


On 18/04/13 11:01 AM, "Koushik Das" <koushik.das@citrix.com> wrote:

>I have some comments inline
>
>> -----Original Message-----
>> From: Prachi Damle [mailto:Prachi.Damle@citrix.com]
>> Sent: Thursday, April 18, 2013 12:17 AM
>> To: dev@cloudstack.apache.org
>> Subject: RE: [PROPOSAL] [CLOUDSTACK-2056] DeploymentPlanner choice via
>> ServiceOffering
>> 
>> Hi Nitin,
>> 
>> Thanks for the feedback. I have added comments inline.
>> 
>> -Prachi
>> 
>> -----Original Message-----
>> From: Nitin Mehta [mailto:Nitin.Mehta@citrix.com]
>> Sent: Wednesday, April 17, 2013 1:42 AM
>> To: dev@cloudstack.apache.org
>> Subject: Re: [PROPOSAL] [CLOUDSTACK-2056] DeploymentPlanner choice via
>> ServiceOffering
>> 
>> Thanks for sharing this with the community Prachi. I read the wiki and
>>had a
>> few questions.
>> 
>> Is there a requirement doc for this ? I wanted to understand the use
>>cases
>> for this.
>> >>This is more of refactoring proposal in order to give more
>>flexibility to the
>> admin  around deployment decisions.
>> >>The typical use-case will be when Admin wants to facilitate
>>dispersion of
>> VMs only for some accounts that need it while for any other accounts
>>that do
>> not care where their VMs land,  keep the deployment random/firstfit.
>> >>Since currently planning choice is governed by the global config
>> vm.allocation.algorithms, Admin cannot make use of the varied deployment
>> heuristics per account needs.
>> >>In the above case, if admin sets this config to 'userdispersion' then
>>the
>> UserDispersingPlanner gets selected for the entire CS deployment,
>>across all
>> accounts.
>> 
>> >>Exposing the choice in ServiceOffering, also lets Admin take care of
>> >>applying any custom pricing for say user-dispersion or
>> >>user-concentrated Vs random/firstfit
>> 
>
>[Koushik] Isn't all the different planning strategies best-effort? In
>that case does it make sense to have custom pricing?
>Also since all the planners are active simultaneously on the same set of
>resources it may result in some randomness. For e.g. if initially the
>firstfit planner is used for allocation of VMs and say it consumes 50% of
>the total resources, after that if userdispersing planner is used then it
>can only disperse VMs within the remaining 50%. Is it ok from admin
>perspective to have this kind of randomness?


Its not best effort. It always applies the algo no matter what but yes the
user might not get the desired results. Or do they both mean the same :).
We are guaranteeing him the algo but not making explicit promise that the
users vm will never be say on the same host. The algo will always be
applied is what we promise.
Example - there are 2 hosts each with 1 user vm and you say user
dispersing planner then it doesn't make much sense using this does it -
but he still pays premium :)

What would be great is say the vm is stopped and there is a 3rd host added
during this time and then when its started back on the 3rd host.


>
>> Since all the attributes are visible in service offering to the end
>>user what is it
>> we are trying to do here ? Give the flexibility to the end user ?
>>Ideally it
>> should give more flexibility to the admin right ?
>> >> Right, Flexibility to the admin. This is not for end-user usage.
>> 
>> You talked about the vm.allocation.algorithms but talking about the
>>planners
>> so I am little confused what is that we are trying to do here.
>> >> This is the config that selects the planner currently. If we refactor
>> >>the planner choice to ServiceOffering, we do not need this variable
>>for
>> choosing a planner We might have to keep this config around in order to
>> provide the choice for host/pool allocation.
>> 
>> I see that Hari also proposed changing vm allocation config to zone
>>level.
>> Is that required any more with this change ?
>> >>I think so, at least not needed to choose a planner since we bring the
>> planner choice to ServiceOffering level rather than Zone.
>> >>Can you please point me to that Proposal? Thanks!
>> 
>> I didn't understand "in a CS deployment multiple planners will have to
>>co-
>> exist." bit can you please elaborate with an example here ?
>> >> After exposing the planners in Svc Offering, some offerings might
>>choose
>> 'FirstFitPlanner', while some other might choose
>>'UserDispersingPlanner'.
>> >>Thus all planners can get used in the same CS deployment - since the
>> choice will no longer be global. All such planners will apply
>>heuristics to the
>> same set of resources - hence they might conflict.
>> 
>> Thanks,
>> -Nitin
>> 
>> On 17/04/13 5:10 AM, "Prachi Damle" <Prachi.Damle@citrix.com> wrote:
>> 
>> >I would like to propose a new feature - DeploymentPlanner choice via
>> >ServiceOffering
>> >
>> >Jira ticket created:
>> >https://issues.apache.org/jira/browse/CLOUDSTACK-2056
>> >
>> >This is to expose the choice of Deployment Planner via Service Offering
>> >and let Admin use a mix of Planners in a CS deployment.
>> >
>> >The initial draft of the FS is here
>> >https://cwiki.apache.org/confluence/display/CLOUDSTACK/DeploymentPla
>> nne
>> >r+c
>> >hoice+via+ServiceOffering
>> >
>> >Please review and comment.
>> >
>> >Thanks,
>> >Prachi
>


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