[Date Prev][Date Next] [Thread Prev][Thread Next] [Date Index] [Thread Index]

Re: replication



On Tue, Mar 18, 2003 at 11:13:50AM -0700, tech@bishop.dhs.org wrote:
> As a favor to a friend, I'm trying to setup a mirror of his server,
> where I can basically be a 'hotswap' for him.  So far, the main problem
> that I'm running into is that everything is ip-based.  For instance,
> it's dead-simple to be a secondary dns server for him, but if his box
> (which hosts dns, web, and mail) goes down, then I'm simply pointing 
> people into dead-space, right?  Well, email is the one standout, where
> the MX records would get them to my machine, but I'm having a hard time
> figuring out how to make web and dns do the same thing.

If you're hosting secondary DNS, it shouldn't be too difficult.
First, change the default TTL of your zone to a very low value, like one
minute. This way you'll almost prevent caching of DNS records on other
hosts.

When your (secondary) machine detects, that the primary one is dead,
you should swap the configuration files for your bind, and make yourself
a primary, and the only one nameserver for the particular domain,
with the addresses pointing to your machine. Reload bind, and from
that moment all HTTP requests should start hitting your server.

You should constantly monitor if the primary machine comes back online,
and if it does -- swap the bind configuration back to original state.

It also means, that you should parse the mirrored httpd.conf and change
the IP in VirtualHost to your address.

I don't think you need any special software -- everything can be done
with a couple of scripts in your favourite scripting language.

Marcin



Reply to: