Re: Webserver Redundacy
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On 28/02/2007, at 12:27 AM, Jim Popovitch wrote:
DNS-based round-robin "load balancing" is pretty useless for what you
want. it doesn't give you redundancy, if one server goes down then
half
the requests will fail.
True. But the client will figure out (in the case of websites)
which IP
to use. So the client experience "just works", perhaps after a bit of
delay by hitting the down server first.
The client doesn't figure anything out.
Either you are lucky, and you get the server that is up - or you are
unlucky - and you get the one that is down.
And seeing how wonderful browsers (and resolver libraries) are, they
have
probably cached the IP address - and you will need to restart your
browser
to try to get to the second and working web server.
The only real way of doing this is as previously suggested, having some
form of IP address takeover system.
Cheers
Andrew
PS: There are some systems out there which fiddle with DNS records,
and set the
ttl to 3 seconds or so - and change your DNS once a server goes down,
but I
would recommend to stay away from this black magic.
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