[hydra-dev] Scalability

[Chris Tooley]

On Fri, Jun 18, 2010 at 3:59 PM, John Todd <jtodd at digium.com> wrote:
>
> On Jun 18, 2010, at 6:52 AM, Ed Guy wrote:
>
>> Do we have any thoughts about the scalability of a hydra system?
>>
>> is it efficient at any level from 1 subscriber to 10 billion?
>>
>> or do we start above the single asterisk box, say at 1000 subscribers
>> And the max, 10 Million subs?
>>
>> This, of course, is an old school way of looking at things, BUT, it
>> is a
>> place to start.
>>
>> Any thoughts on concurrent sessions?
>>
>> or other scaling metrics?
>>
>>
>> /ed
>
>
>
> Well, I think it's close to being reasonable.  However, I'm uncertain
> if "subscribers" is the right measure.  I'd say "channels" or "active
> communications" or something a bit less oriented towards a commercial
> relationship and more to a functional expectation.  A "subscriber" is
> someone who has some unknown amount of idle time, and with new
> versions of communications popping up that have unknown maximum busy
> hour transactions (chat, video, smell-o-vision) we can't really base
> the system on future unexpected user behaviors.  We perhaps may wish
> to use instead a count of active communications paths...?
>
While I don't completely disagree with the "active communications
paths" being the largest burden on the system, "subscribers" have a
demonstrative impact on the performance of the system as a whole. In
all likelihood the subscribe, "are you still there", "where are you
at", and unsubscribe control communications for a subscriber will
account for a large volume of traffic as a whole than active
communications to/from that subscriber (except of course in cases like
RTP). Thinking specifically of SMS or IM protocols the awareness of
the endpoint can end up accounting for more traffic than the actual
initiated communications.

> This brings into question how asynchronous communications are counted,
> and I'm not sure how to consider that.  Maybe our concept of
> "channels" is based on the idea of 'communication packets flowing at
> least once per second' or some measurement like that.  But I don't
> want to fall too deep in that rathole when an 80/20 rule will work
> quite well here (but I'm not sure that "subscribers" is an 80/20-
> compatible number, which is why I comment here.)
>
> JT
>
>
> ---
> John Todd                       email:jtodd at digium.com
> Digium, Inc. | Asterisk Open Source Community Director
> 445 Jan Davis Drive NW -  Huntsville AL 35806  -   USA
> direct: +1-256-428-6083         http://www.digium.com/
>
>
>
>
>
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