ArcGIS Enterprise 11.3 - Replace the Web Adaptor Server with Same Configuration

[Hua]

Hi ArcGIS Enterprise community,

This is a question about the web adaptor server role.

Background
We have an ArcGIS Enterprise 11.3 standard multi-machine deployment. Three web adaptors are installed on a single server - one is for the portal, and two are for ArcGIS servers/sites.

The Task
For some reason, we have to replace this web adaptor server. The good news is all the configurations will be identical to the existing one. No changes to the URL and instance names.

The Question
Since there are no changes to the instance names and URLs, the only change is the machine name. Is the process straightforward as below?

1. Prepare the new server to replicate all settings as the existing one, including firewall, IIS settings, SSL certificate, etc.

2. Unregister the web adaptors from the Portal Admin Directory and Server Admin Directory.

3. Install 3 x web adaptors on the new server with the same configuration as the old one.

4. Post-installation - DNS, load balancer to point to the web adaptor server.

I would appreciate it if someone could point out if I have made a mistake or missed anything.

Thanks,

Hua

[DavidColey]

I would say you need to handle any DNS and load balancing as part of step one.  That all needs to be in place before you install the web adaptors and re-register your portal and server sites.

For us, we use an F5 switch outside of the DMZ.  Our web server lives inside the DMZ, and its alias */.ags3.ourorg.net/ is named on the F5, not as part of the DNS. So, the FQDM and the DNS are the same, because there is no DNA alias. 

We do this so that the wildcard CA certificate we use for the enterprise is valid across the deployment.

[JoshuaBixby]

The best way to know if it works is to test it, that is why you should have a test or staging environment, or maybe even just a development environment.  Without testing, even the best plan that should work can go wrong and have unexpected consequences.  Overall, the steps look fine, but there will be a brief outage between step 2 and 4 since there will be no registered Web Adaptors but users may still be attempting to connect using the Web Adaptor address.

[Hua · Accepted solution]

Thanks for the advice. Just completed the change, everything went well, no surprises.

I took  @DavidColey's advice to have a temporary 'GIS system under maintenance' home page set up on the new web server and had IT update the internal DNS CNAME to point to the new server before I started doing any actual unregistering and installation.

So the high-level steps are:

1. Prepare the new server to replicate all the existing settings, including the firewall, IIS settings, SSL certificate, log cleaning scheduled tasks, etc.
2. IT to update the internal DNS/CNAME registry to point to the new server. The new server has a maintenance home page set up.
3. Enable PSA account on GIS servers if they are disabled.
4. Unregister the web adaptors from the Portal Admin Directory and Server Admin Directory.
5. Install 3 x web adaptors on the new server with the same configuration as the old one.
6. Post-installation testing

I handled one adaptor at a time, i.e. Unregister WA -> Install WA on new server -> Config -> Verify. The order of the WAs I did was Non-hosting GIS Server -> Hosting GIS Server -> Portal. 

Critical things - WA instance name remains the exact same to ensure federation won't break.

Cheers,

Hua