Re: Migrating from one server to another

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Date:         Fri, 18 Jun 2004 21:07:49 +0200
To: aix-l@Princeton.EDU

We had some problems at the start with the network switches,
because they weren't updating their arp cache when the alias got
moved to a different box: took thirty minutes to refresh, or taking
the interface down and up again. That was sorted out by one of my
colleagues, but I forget how. Since I'm going home in a minute, I
can't be bothered to look it up, either. :-)

We've also had a problem on some servers where there are lots of
aliases - >10? - where one of the aliases seems to become the
"primary" address - top of the list in netstat -i. When you
unconfigure that alias to move it somewhere, it takes the default
gateway with it and also messes up the routing table in some
as-yet vague and undetermined way! (I think that it retain an
entry for that interface with the alias address, instead of having
the correct non-alias address.) I've only seen this once for sure,
but I think it's actually happened twice. We haven't been able to
reproduce the problem, though.

We had a problem once when we added an application alias that was
in a different subnet to the primary. Subsequently, connections
to other nodes in that second subnet failed, because IP thought
they were local, and didn't send them to the gateway. That's not
really a problem with the concept, though, just an administrative
error.

There may be some issues with older versions of HACMP, but I think
current ones should cope with it.

rsh, ftp etc work fine to the aliases. We don't do NFS mounts
using the aliases, though. (I think that could cause some
confusion with exports, although I don't think it would be difficult
to sort out. But we intend the aliases to be used by *users*, not
for actually configuring stuff on the servers themselves.)

Aliases are added through a script we set up, with a centrally
maintained list of aliases. We do not have them in the ODM. That
makes it easier to move them around without having to remove the ODM
entry: just change the master config file and push it out with rdist.

We're very happy with the way it all works.

--
Simon Green
Altria ITSC Europe Ltd
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> -----Original Message-----
> From: Bill Verzal [mailto:BVerzal@KOMATSUNA.COM]
> Sent: 18 June 2004 19:44
> To: aix-l@Princeton.EDU
> Subject: Re: Migrating from one server to another
>
>
> Nice concept.  I think I'll store that in the back of my
> head.  Have you
> come across any issues with that procedure ?

• Previous message: Bill Verzal: "Re: Migrating from one server to another"
• Maybe in reply to: Adam Hanel: "Migrating from one server to another"
• Next in thread: Coonfield, Ben: "Re: Migrating from one server to another"
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