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From Murali Reddy <>
Subject Re: [DISCUSS] Global Server Load Balancing (GSLB) FS & Design Document
Date Mon, 21 Jan 2013 04:33:28 GMT
Thanks for the review. Please find the comments inline. In this spec I
tried to captures what I think will be high level design of this feature.
Specifics on the finer implementation details will be clear as I progress
with development. I will update the spec when feature in decent shape.

On 18/01/13 6:03 PM, "Venkata SwamyBabu Budumuru"
<> wrote:

>Hi Murali,
>I am planning to take the QA job for this feature. Have reviewed the
>functional spec and have the following questions
>1. As per the FS, we are going to have a region and zone level flag for
>GSLB capability. Why do we need a flag to be set at zone level ?
>As the cloud admin is going to enable GSLB service provider at physical
>network level, can we use this info to decide whether this physical
>network is enabled and used for GSLB rather at zone level

Yes, GSLB provider is enabled/disabled can be used to infer zone is
enabled/disabled for GSLB.

>2. Are we going to use the same cloud. physical_network_service_providers
>table to store the services GSLB offering? Do we have the list of
>services which GSLB is going to offer? Can we add those db changes to FS?

GSLB provider is only going to offer GSLB service. I will update the spec
on how GSLB provider added into zone should be persisted in the DB.

>3. Is the createGlobalLoadBalacerRule takes the weight parameter along
>with "lb algo"? can we update the same to "API Changes"?

Weights are for individual 'virtual servers'. Its added in the
'assignToGlobalLoadBalancerRule' API mentioned in the spec.

>4. "Functional Requirements" sections says "statistics shall be collected
>for each of GSLB virtual server."
>	a. What kind of statistics? Is it the statistics that give a picture
>about which site has more hits, load etc.. so that user can adjust the
>weights associated with virtual server to balance things?
>	b. Are we also considering the traffic / bandwidth consumption resulted
>by request redirection from one site to the other (due to proximity or
>weight etc..)? are we recording those usage statistics  for billing ?

I have not investigated much into statistics aspect at this point. But I
do see the ADC providing stats for GSLB services.

>5. what is the health monitoring workflow? Like if SLB vserver is down /
>GSLB vserver down. Is the CloudStack aware of this and reacts to it?

At GSLB level, GSLB providers are supposed to do the health monitoring of
service across zones and ensure the service availability.I do not expect
CloudStack to take any action based health of service at a zone. But SLB
level, CloudStack can perhaps create/add/destroy load balanced instances.
'AWS style health check' feature which Rajesh has praposed might be
dealing with it. 

>6. Can the cloud admin use same device to host GSLB vservers and SLB
>vservers ?


>7. Is the planned design going to accommodate multiple devices
>(NetScalers) for hosting GSLB vservers in single physical network?

I will assume one GSLB provider per zone for now.

>8. SLB provider can be anything right? It can be VR, VPC VR, VPX, etc..,?


>9. Current design is considering requests going from GSLB virtual server
>to SLB vserver and how about a use case where user want to use GSLB to
>load balance request across zones that goes to  static NAT rule / PF

GSLB is used primarily in the context of LB. Scope of this proposal is
restricted only to LB.

>10. Is it a requirement in public clouds where tenant would ask for /
>wants to have his own domain name rather using * did we
>consider such usecases in this design?

One could use CNAME's (outside scope of CloudStack) that maps to cloud
provider specific domain name.

>11. Can you also add all the admin API changes?

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