Re: seemless migration
Not only are these comments welcome, they are greatly appreciated. This
was the type of discussion I was hoping for!
Dan MacNeil wrote:
> 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
> 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.
Simply change the a record for the primary name server to the duplicate
machine while the glue record is propagating? I hadn't thought of this.
> 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.
While I have a written play-by-play calendar plan, this will certainly help!
> 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.
agreed. Though I'd sure like to get this behind me. I'm sweating bullets
> 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.
For 1 to two weeks. I had completely forgotten I could do this with
debian. I just now found the below example.
iface eth0:0 inet static
iface eth0:1 inet static
> 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.
If I haven't said it clearly enough, thank you very much. 2 or three
heads are always better than one. The input makes me feel better and
introduces more alternatives.
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