Re: seemless migration
A few random thoughts based on a couple recent moves we've had to make,
much of this is probably obvious or irelivant to you.
Moving DNS server IP numbers is different than changing ip# that they
serve.
You don't control the TTL (time to live) at the
root servers. You need to change your DNS
servers ip# now and leave the old ones running
serving the correct ip# for the new DNS server.
You also need to change the glue record for your
DNS servers at your domain's registrar. Usually
this is something like "add IP# for DNS server"
Even in a well setup system, there are some settings that depend on hard
coded ip#. Firewall rules, postfix "mynetworks", etc. It is probably worth:
sudo grep $OLDNET /etc/* -d recurse -l
...on all your systems.
You almost certainly do not have to move every thing all at once. If you
move one server at a time, you can learn from your experience and maybe
get a night's sleep between moves.
If there will be overlap between your two T1 vendors, you can run your
servers with both the old and new ip numbers for a time.
If some of your customers are running their own DNS (like at
register.com), you should let them know of the move.
You want to adjust both $TTL and the SOA TTL , the later controls
negative caching, how long "not found" result is cached.
DNS checking tools, http://dnsreports.com are useful
If you are running on a T1, you can almost certainly drop TTL to 1
minute. --load on DNS and pipe won't be that high.
###########
Rodney Richison wrote:
Hi
Need to migrate a group of servers to a new T1 line as smoothly as possible.
These servers include all the usual. Dns, mail, http etc.
The reason is, Birch Telecom is getting out of the T1 bussiness and
dropping all the customers. The new provider will be at&t so this will
NOT happen again.
Birch will drop service on Jan 30. The new line will be installed on
Jan 18.
That doesn't leave much time to mess around.
Primary name server plan:
The plan is to duplicate the primary dns server. One week before the
switch, change the ip at the root. This will bring the primary down
ahead of time but give the world plenty of time to make the switch.
Meanwhile the 3 secondary's can handle things... As the original primary
continues to supply the secondaries..
Sites/Servers plan:
Set all ttl of all dns to 10 minutes 1 week ahead of time.
As soon as the new line is up and reliable, change both primary name
servers with a prebuilt bind setup. Ugghh Sounds like fun. :)
Then, Switch all servers to the new line and pray...
Any thoughts or suggestions or comments would be greatly appreciated.
--
Dan MacNeil <dan@thecsl.org>
Fearless Leader, Community Software Lab
http://thecsl.org/go/vol
God has no hands or feet or voice except ours, and
through these, God works. (St. Teresa of Avila)
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