[rescue] web server loadbalancing...

[Greg A. Woods]

[ On Thursday, August 2, 2001 at 16:25:00 (-0500), Reagen B . Ward wrote: ]
> Subject: Re: [rescue] web server loadbalancing...
>
> On Thu, Aug 02, 2001 at 04:10:01PM -0400, Greg A. Woods wrote:
> 
> > well not built-in, but you can change rdr rules on the fly and a little
> > watcher script that can do the right thing shouldn't be hard to concoct.
> 
> Same goes for RR DNS, minus a layer.

Huh?  Round-robin DNS actually adds at least one layer over and above
what any server-fronting load-balancer solution adds, and perhaps even
more (one for each extra nameserver in the path)!  And that's assuming
_all_ your clients actually do even close to the right thing with more
than one A RR....

Not to mention but use of RR DNS also enforces at least a 300 second
interval between changes that can be propogated out to clients too
(minimum TTL honoured by any RFC-conforming DNS cache is 300s).

> More importantly, this isn't very useful for things like ecommerce or
> other sessions that require you to hit the same server as last click.

Well, that's a whole different issue, and one that I personally think is
bogus too (caused by lazy back-end programmers!).  Also note that if you
buy into this scenario there's an even larger gap between what's
necessary for true "load balancing" and "backup failover" too!

-- 
							Greg A. Woods

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