Curtis Maloney wrote:
> On Thu, 20 Jul 2000, Bill Anderson wrote:
> > Toby Dickenson wrote:
> > > On Tue, 18 Jul 2000 16:08:48 -0600, Bill Anderson <[EMAIL PROTECTED]>
> > >
> > > wrote:
> > > >> I might be reading more into his words than was intended, but I think
> > > >> this demonstrates the problem. Distributing multiple requests for one
> > > >> section across multiple servers is (what I consider to be)
> > > >> undesirable.
> > > >
> > > >You can actually do it either way. Curtis (AIUI) complained that the
> > > >method described meant your site depended upon each of th esection's
> > > >servers being up, that there was no redundancy. So I described a way of
> > > >doing it with redundancy.
> > >
> > > What you described doesn't scale up to having 1000's of sections
> > > (which I was assuming, and I think Curtis was too).  If this isn't a
> > > problem, then your solution is great.
> >
> > I don't understand why you think it doesn't. DNS has clearly
> > demonstrated the ability to handle 'thousands', and the entire
> > scalability of a cluster is the addition of machines. You appear to be
> > desirous of having a machine handle a section. Thus, for thousands of
> > sections, you have thousands of machines. Again, with a ZEO clusters the
> > bottleneck/SPOF would be the ZSS, but that _could_ be worked aorund, and
> > has nothing to do with 'sections' of a website.
> >
> Bill,
>         Whilst the structures you've described are very effective, your example of
> required one thing in particular that I'm not sure is available:
> prior knowledge of which sections will be hit hardest.

You start with the most likely suspects, and then after a given time
interval, you adjust as needed. *most* site admins have a good idea of a
given section being more popular or frequented when the site is built.
That is as good a start as any other, if not better.

>         Essentially, your setup allows any 'server' to become a 'server cluster' for
> scaling purposes.  Great!  So, if for now on we assume 'server' can mean
> 'single or cluster of servers'....

A logical assumption.
>         The desire isn't for fixed server<->section relationship.  Instead, a
> 'preference' for that section to go to a particular server, so that the
> request 'hopefully' goes the server with the greatest chance of having the
> relevant objects in cache.

I see that it may not have been clear, but my ecample provided just
that. A preference is indicated by the weight given to servers and
sections. Let us say I have three servers. Fo rthe whole site, two get a
weight of 2, whilst a third gets a weight of 1. This third one, however,
gets a weight of 2 for the members section, whilst the other two get a
weight or 1. This provides a preference for server3 to serve up the
members section, though it is not a direct-only mapping. how does this
not fit the 'hopefully' desire?

If you _wanted_ a direct-only, you simply remove servers 1 and 2 from
the list of the members section. The really neat thing about this is
that it can be done at runtime.
>         In fact, with the further information provided, what you really want is for
> requests from a particular client to go to the same server.  This would be
> better served with a redirection to a server specific domain name
> (  However, for the initial request, your best choice is
> to go to the server that last served those pages.
>         Since dynamically tracking this info would be onerous, by encouraging
> requests for one section toward a particular server, you improve the chances
> of it holding the relevant objects in cache, with merely a fraction of the
> processing/data overheads.

Right. I agree that tracking all of this would be onerous, which is why
I said I don't think it is worth the effort, and would cost more than it
saved. The scenario I described gives a preference for sections to go to
a particular server, thus giving you the 'encouragement'. :^)

> > Beyond that, your bottleneck would be networking. Whether yoour
> > individual BE servers responded directly to the web browser, or whether
> > they were channeled through a single/multiple FrontEnd servers. The
> > decision to implement a BE->Client vs. a BE->FE->Client topology has not
> > been discussed, as it is irrelevent to the discussion.
> Ah, topology.  (I'm leaving it there.  I really don't have time to get into
> this fully :)

Yeah, topology is where the umm ... electrons hits the wire.
Mebbe I'll post this stuff to the Wiki ... the question is .,.. which

Do not meddle in the affairs of sysadmins, for they are easy to annoy,
and have the root password.

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