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From Chiradeep Vittal <Chiradeep.Vit...@citrix.com>
Subject Re: AutoScale feature....
Date Tue, 03 Jul 2012 01:42:32 GMT


On 7/2/12 6:24 PM, "David Nalley" <david@gnsa.us> wrote:

>On Mon, Jul 2, 2012 at 2:08 PM, Ram Ganesh <Ram.Ganesh@citrix.com> wrote:
>> Hi All,
>>
>> Briefly talking about the feature - AutoScale feature allows you to
>>scale up or scale down the virtual instances that are being load
>>balanced by load balancers like NetScaler based on certain conditions.
>>This feature is an extension to the ELB feature in CloudStack. This
>>feature is similar to AWS autoscale feature except that monitoring of
>>server's(guest vm) health is done by load balancers like NetScaler and
>>provisioning is done by CloudStack. Monitoring done by loadbalancers has
>>couple of benefits
>>         - Loadbalancers are better placed to understand the health of
>>the  server as traditionally LB devices had monitoring capability
>>inbuilt in it.
>>         - Decisions can be based not just on certain conventional
>>counters like CPU, Memory etc but also on network counters like response
>>time, bandwidth, connections etc
>>         - Decreases the load on CloudStack management server.
>
>But that inherently limits where AutoScale will work. This means all
>of this work is inherently very niche, can only be tested by folks
>with NS hardware,  and only utilized by the same folks - and
>autoscaling could be inherently useful in other situations that don't
>have LB implications.
>CloudStack has inherently been hypervisor agnostic, is there a reason
>not to be LB agnostic as well?

It seems to me that the proposed APIs are not too LB-specific (there's
stuff about snmp ports and community strings that is specific to this
implementation and should not belong in a generic API).
I would imagine that an auto scaling implementation would have:
1. Monitors that know how to monitor a specific kind of load
2. Configuration of thresholds to get notified when the monitors detect a
breach of thresholds
3. Actions to take on breach of thresholds

I would like to see a generic framework such as this laid out and a
description of how this specific implementation uses the framework.

Also, the FS template has lots of questions
(http://wiki.cloudstack.org/display/RelOps/Functional+Spec%28FS%29+Template
) which have not been answered.


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