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BDunbar_102927's avatar
BDunbar_102927
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Jul 25, 2011

Upgrading application - how to keep the DNS name?

Is there a way to have traffic for OLD and NEW IIS servers to use the same DNS name?

 

 

 

 

We have an application, FOO. Two IIS servers behind the F5, standard port 80 setup. It's an internal-facing application, not public access allowed.

 

 

The virtual server IP has a DNS hostname of FOO.company.com

 

 

We'd upgrading FOO to a new version, FOO version 2. We must run the original FOO while we migrate users to FOO 2. They'll be running parallel for a month in production, at least.

 

 

The application team, just this morning, said 'The server is now running IIS. Time for the F5!'

 

 

'So what do you want your new DNS name to be,' I replied.

 

 

'Can't we keep the old one? foo.company.com is pithy and the users like it.'

 

 

'Well, you know the F5 is not my primary job and I only know a little bit about it.'

 

 

Long faces all around.

 

 

'But,' I continued 'I'll see if there is a way to use 'foo.company.com' for both the old and new hosts.

 

 

 

So how about it? Two applications, two IIS hosts, one F5: one DNS name.

 

 

I'm aware that companies with non-captive users have this dilemma and THEY manage to do it. So why oh why can't I?

 

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  • Mark_Cloutier's avatar
    Mark_Cloutier
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    Jul 25, 2011

    I usually setup a new virtual server, called foo-new or foo-mig (migration) for example, and have a pilot group of users test the app using the new name. Once the new app is "proven" ready for prime time, I add the new server(s) to the pool serving foo.company.com, and disable the old server(s) in the pool. Then if for any reason you need to revert to the old app, simply disable the new servers, enable the old... After some period of time that you feel really comfortable with the new servers, simply remove the old servers from the pool.

     

     

    If you really want to have one virtual server served by two pools, you could get creative with an irule and define a pool of addresses representing the group of users that you want to send to the new pool, then have the irule choose a pool of servers based on what pool of addresses they came from, but if you are new to using F5's that's probably more risk than its worth....