Running Central Admin on Multiple Servers within a Farm
One of the best practices that the Premier Field Engineering (PFE) team always recommend is to run the Central Administration Web application on multiple servers (at least 2) within the farm. Then if anything happens to one of the servers hosting Central Administration you can still manage MOSS 2007 - the alternative is provision and configure Central Administration on an existing server using stsadm - not a good situation to be in, especially if you desperately need access!
Whilst this is fairly easy to setup either during the Post Setup Configuration GUI, via the command line and even via Central Admin itself (targeted at other servers within the farm though obviously) customers often run into issues when trying to access the second instance of Central Administration.
For example my farm includes three servers:
· Server1 – Web Front End
· Server2 – Web Front End
· Server3 – Application
When I originally created the farm I configured Server1 to host Central Administration (this was the first server that was built) I then built Server2 and choose to host Central Administration on this server too. It was decided that Server3 would be completely dedicated as an application server so Central Administration was not provisioned on this server.
If I look in IIS Manager on Server1 I can see a Web site for Central Administration, listening on port 40000 with no host header, therefore available via the URL http://server1:40000
If I look in IIS Manager on Server2 I can also see an identical Web site listening on the same port, therefore available via http://server2:40000
If I then launch Internet Explorer from my desktop and browse to http://server1:40000 Central Administration is displayed within my browser and I can configure MOSS 2007 as I please!
Now one day I decide that I don’t want to access Central Admin on server1 and would prefer to use server2, so I type http://server2:40000 in my browser and connect to the site – but wait a minute it has redirected me to http://server1:40000 this isn’t very good, what would I do If server1 was unavailable and I needed to access Central Administration!
The behavior that you are seeing is expected and is the default behavior; with a minor configuration change to Alternate Access Mappings (AAM) you can configure Central Administration to be available on both URLs without it doing the pesky re-direct J
To accomplish this you will need to Launch Central Administration and select the Operations tab, then select Alternate Access Mappings from within the Global Configuration section.
In the top right there is an option for Alternate Access Collection, select this and choose the Central Administration Web application.
In my example I then see the following:
As you can see server2 has an entry within the Internal URL section but not within the Public URL for Zone. I won’t bore you with the technicalities of AAM, if you are interested you may find the following useful - http://technet.microsoft.com/en-us/library/cc263521.aspx
To get this to work as expected we need to add a public URL entry for server 2; this can be done as follows:
1. Select Edit Public URLs
2. Add an entry for server 2 – I generally use the Intranet zone and then click Save
3. Alternate Access Mapping should now look as follows
You should now be able to access Central Administration on server1 and server2. One thing to note is that the link within the Start Menu to Central Administration will always point to the first server that Central Administration was installed on, which is the server that was used to create the farm (in my case server1) although this can be changed via the registry.
Brendan Griffin
