[occi-wg] Horizontal & vertical scalability in the cloud

Sam Johnston samj at samj.net
Sun Oct 25 22:39:03 CDT 2009


On Mon, Oct 26, 2009 at 5:27 AM, Gary Mazz <garymazzaferro at gmail.com> wrote:

> I believe we had discussed this issue some months ago (CCIF ?) and reached
> agreement that none of us wanted to be business of formulating cloud
> benchmarks. :-)

I think cloud benchmarks are relatively safe provided they are not
considered "universal" - there are a myriad tests for PC performance today
and each represents a different workload. Microsoft have got about as close
as you will ever get with their Windows 7 performance indexes, but even they
are specific to the task of running an interactive windowing interface.

> Is something like TCPC effective or any of the apache server workload stuff
> applicable, I really couldn't say.  I like the approach the UNSW took, it
> looks like a good starting point. I don't have time to contact UNSW this
> week, but it may be work while to approach them.

I think the best approach is to have trusted third-parties (like Anna's
team) conducting batteries of tests with the approval (but probably not
direct knowledge of which accounts/when) of the cloud providers. It's
certainly not realistic to have every tire kicker running their own suite of
tests and indeed to do so without prior notice could reasonably be
prohibited by terms of service. Each service would then have a set of
figures and users could use those most appropriate for their workload.

Agreed on keeping the clones to identical characteristics, I'm not sure how
> feasible that is today. But, it a good, practical way to initially define
> it.

I'd be satisfied with a "should" requirement level for clones being
identical - it's almost always going to be better that a request be
satisfied with a mix of hardware than not at all.


> Sam Johnston wrote:
>> Gary,
>> I think you've touched on an interesting point there which ties in to the
>> "need" for a universal compute unit. More specifically, "cores" aren't a
>> standard unit of measurement (at least without arch and speed), and in any
>> cloud that's not brand new you're going to end up with a mix of core speeds
>> depending on what presented the best value at
>> build/replacement/expansion/failure time.
>> If you have a mix of core speeds at a given tier without sufficiently
>> intelligent load balancing (e.g. response time based) then you'll end up
>> with some cores being underutilised and/or finishing jobs faster, and others
>> being unable to keep up. If you're applying the buffalo theory (e.g. round
>> robin) then you're only as fast as your slowest machines.
>> Simple fix is to ensure that "clones" or "shadows" of a given compute
>> resource are all identical, but it's worth keeping in mind nonetheless.
>> Sam
>> On Mon, Oct 26, 2009 at 4:22 AM, Gary Mazz <garymazzaferro at gmail.com<mailto:
>> garymazzaferro at gmail.com>> wrote:
>>    'horizontal' and 'vertical' dials is a good idea to define.
>>    @Andy,  I'm a little confused on the definition of horizontal
>>    saleability. Aren't the cpus in a single operating image a vertical
>>    workload capacity much like the amount RAM . If the number of images
>>    scaled, that would be horizontal because there is no necessity for the
>>    images to be the same workload set.
>>    I would prefer to see the dials tied to a standard "meter of work". An
>>    efficiency metric instead of an "equivalence" of cpu count and ghz and
>>    RAM amount. Juggling these dials may not be as effectual as the
>>    consumer
>>    perceives when a provider decide to throttle back performance and
>>    starts
>>    dropping workload requests. Without a referenced  "effective workload"
>>    metric, it may be tough to ascertain if the dials effect anything,
>>    other
>>    than the charge to the customer.
>>    gary
>>    Randy Bias wrote:
>>    >
>>    > On Oct 25, 2009, at 5:38 PM, Sam Johnston wrote:
>>    >> A better approach to scalability is to have a single object
>>    which you
>>    >> can both adjust the resources of (vertical scalability) and adjust
>>    >> the number of instances of (horizontal scalability). That is, you
>>    >> start a single instance with 1 core and 1Gb, then while it's
>>    running
>>    >> you crank it up to 2 cores and 2Gb. Eventually you max out at say 8
>>    >> cores and 16Gb so you need to go horizontal at some point. Rather
>>    >> than create new unlinked instances the idea is that you would
>>    simply
>>    >> adjust the
>>    >
>>    > I agree.  This is the future.  Dials for 'horizontal' and for
>>    > 'vertical', probably attached to a given tier of an application.
>>    >
>>    > Just as an FYI, I think 'scale-up' VMs are going to be more and more
>>    > common.  We'll see VMs with a *lot* more RAM and cores very soon
>>    now.
>>    >  Most of the modern OSes handle hotplug of CPU/RAM pretty well.
>>    >
>>    >
>>    > Best,
>>    >
>>    >
>>    > --Randy
>>    >
>>    >
>>    > Randy Bias, Founder & Cloud Strategist, Cloudscaling
>>    > +1 (415) 939-8507 [m], randyb at cloudscaling.com
>>    <mailto:randyb at cloudscaling.com>
>>    > <mailto:randyb at neotactics.com <mailto:randyb at neotactics.com>>
>>    > BLOG: http://cloudscaling.com/blog
>>    >
>>    >
>>    >
>>    >
>>  ------------------------------------------------------------------------
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