Re: Workload for surrogates

From: Mark Nottingham (
Date: Thu, Aug 17 2000

  • Next message: "Re: Workload for surrogates"

    Date: Thu, 17 Aug 2000 11:40:10 -0700
    From: Mark Nottingham <>
    To: Fred Douglis <>
    Message-ID: <>
    Subject: Re: Workload for surrogates
    Characterizing CDNs is shooting at a moving target; each one is going to
    take a different tack at how it handles objects, and what gets routed
    through the CDN. so-called "edge processing" throws another wrench into the
    works, as each one will have a different approach.
    Of course, all surrogates are not used in CDNs; "reverse proxies" are
    somewhat widely deployed on popuular sites (that's a feeling; I haven't seen
    much data to support it).
    I'd think two workloads would be in order; one to represent a surrogate in
    front of an entire, "typical" site, and one to represent a CDN that handles
    all cacheable objects. 
    These would only give rough figures, of course, but that's about the best
    that can be done IMHO, and they would still be useful to compare.
    On Thu, Aug 17, 2000 at 09:33:41AM -0400, Fred Douglis wrote:
    > [Cross-posted to wca list from surrogates list.  Original message attached.]
    > Ted,
    > Regarding CDNs, since in general there is a tendency toward emphasizing 
    > cachable content up front, I would expect the workload to be somewhat 
    > different from a typical origin server, at least one that has any significant 
    > dynamic data.  There'll be a greater fraction of hits to more static content 
    > such as gifs.  
    > I know there's been some work on benchmarking CDNs but I don't know if there's 
    > been work on characterizing behavior.  The W3C workload characterization group 
    > might be looking into this -- have you asked around there?  I'm cc-ing them 
    > here.  Perhaps someone will have additional info.
    > Regards,
    > Fred
    Content-Description: 4
    > Date: Wed, 16 Aug 2000 14:00:08 -0700 (PDT)
    > From:
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    > To:
    > Cc: (ted hardie)
    > Subject: Workload for surrogates
    > Delivery-Date: Wed Aug 16 17:15 EDT 200
    > X-Mailer: ELM [version 2.5 PL3]
    > As part of the testing of the Bellwether surrogates implementation,
    > Duane and I have been talking about what the workload for a demand
    > driven surrogate would look like.  We've been testing both single
    > surrogate and load balanced surrogates using a polygraph workload that
    > presumes a fairly high hit rate.  This derives from our model of a
    > surrogate that gets invoked by periods of high demand for a limited
    > data set (the flash crowd/CNN event effect typical for a Starr report
    > release).
    > Thinking about this, though, I've been wondering what other types of
    > workloads might be common.  CDNs seem likely to have a workload
    > close to an origin server, where some demand-driven surrogates might
    > have a workload like a proxy cache.  
    > Any insight out there on what you expect or what you have seen in
    > initial deployments?
    > 			regards,
    > 				Ted Hardie
    > 				Equinix, Inc.
    Mark Nottingham, Research Scientist
    Akamai Technologies (San Mateo, CA)