SharePoint 2013 upgrade preparation - redirect only migrated site collection

As we discussed before, there are many options to redirect old site collection URLs to new URLs to avoid URL changes or downtime SharePoint 2013 during upgrade. 

We have a situation that users from one department need to upgrade their SharePoint 2010 sites across several webapps to 2013 while other users will stay on 2010 version for some time. The best option is to use AAM redirect. In this blog, I'll explain how to implement this and how to maintenance this. There are some issues associated with the approach will be listed here.

SharePoint 2010 http://sbx18/sites/R1/ has been upgraded and migrated to http://sbx28:13247/sites/R1/ and no of the other sites http://sbx18/**  have been upgraded. Th goal is to redirect only upgraded site like R1 to new SharePoint farm. Here are the procedures.

 1. Use powershell to verify existing AAM -  stsadm -o enumalternatedomains -url http://sbx18
 You should see the following result with no AAM mapped:

            <AlternateDomains Count="1" Name="SharePoint - sbx2080">
                   <AlternateDomain>
                        <IncomingUrl>http://sbx18</IncomingUrl>
                        <UrlZone>Default</UrlZone>
                        <MappedUrl>http://sbx18</MappedUrl>
                        <RedirectUrl />
                    </AlternateDomain>
               </AlternateDomains>
 
2.  USe powershell to add redirect URL - stsadm -o addzoneurl -url http://sbx18 -urlzone Default -zonemappedurl http://sbx18 -redirectionurl http://sbx28:13247
You should see the following result with new URL mapped:

            <AlternateDomains Count="1" Name="SharePoint - sbx2080">
                   <AlternateDomain>
                        <IncomingUrl>http://sbx18</IncomingUrl>
                        <UrlZone>Default</UrlZone>
                        <MappedUrl>http://sbx18</MappedUrl>
                        <RedirectUrl>http://sbx28:13247</RedirectUrl>
                   </AlternateDomain>
               </AlternateDomains>
  
3. Any site on the webapp http://sbx18 will be redirected to new webapp http://sbx28:13247 if not found on the original webapp. If the site URL exists on old server, it will display directly on old server.

This looks like perfect and it could be used if you move site from one webapp to another with same SharePoint version. However, there are some limitations described below you need to be aware of to maintain the system.

The first limitation is although some functions like OoB web services http://sbx18:13247/sites/R1/_vti_bin/Lists.asmx will be also redirect, several accesses will not be redirected. These accesses include access from WevDev, Outlook, and SharePoint designer. You might need to communicate with users if they access SharePoint through other channels besides UI.

The error you got from designer is as below.

The second limitation is you could add only one URL to redirect all sites inside one webapp. You could not redirect some sites to one URL and other sites to a different URL. The last URL mapping set through powershell will overwrite existing one.

The third limitation is there is not documentation to remove the mapped URLs after set up. You will get error or run into loop if you try to do the following powershell commands.

stsadm -o deletezoneurl -url http://sbx18 -urlzone Default

stsadm -o addzoneurl -url http://sbx18 -urlzone Default -zonemappedurl http://sbx18 -redirectionurl http://sbx18

The way to remove the AM mapping is to use the following command. Do not include the -redirectionurl parameter, otherwise you’re redirecting to the original address, in a loop. Remember to verify use enumalternatedomains powershell command to verify the result.

stsadm -o addzoneurl -url http://sbx18 -urlzone Default -zonemappedurl http://sbx18

As we discussed here, it's a good option to redirect only some site collections inside one webapp. After you upgrade and migrated the whole farm, you should use other options or not even use redirect as discussed before.