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New Member

multiple unity servers require a global catalog server?

I have a customer that will have 3 Unity servers. Is there a good reason why they might need a separate server acting as the global catalog server? Can't one of the Unity servers act as the global catalog server too?


Re: multiple unity servers require a global catalog server?

Is this a VM only deployment where Unity resides in its own domain or unified messaging where Unity is connecting with an existing directory/messaging infrastructure? If VM only, certainly one of the Unity servers can act as a GC. If unified messaging, normally an existing domain controller(s) will act as a GC.

Hope this helps. If so, please rate the post.


New Member

Re: multiple unity servers require a global catalog server?

This is a VM only. Is there a benefit to have a stand-alone global catalog server?

Re: multiple unity servers require a global catalog server?

I can't see that you would gain anything (except another box to maintain). Unity would still have to write changes to the directory and poll the GC for changes using the AvDSGlobalCatalog service whether it's on the same server or on a different box. Take a look at the following link for an overview of how Unity interacts with the directory and global catalog.

Cisco Unity Data and the Directory


Re: multiple unity servers require a global catalog server?

I had this debate a little while ago. I think you should have a seperate server to handle the GC role in AD. With 3 Unity servers, or do you have 2 unity servers and 1 messaging server? If you do.. you could potentially throw alot of subscribers on Unity/Exchange. The read/write load on the Exchange would take it's toll eventually. But if you are under 1000 users, you should be ok with a dedicated GC. The GC is just nice to have to load off Exchange and/or a Unity servers. MS recommends you not load an Exchange Server as a GC server. Most people who load Unity in VM only will do just that because it's not completely critical. But here is where the DC/GC role comes into play.

What if your Exchange server crashed... The mirror broke and you have a crappy backup...DIRT will not cover AD errors after it's rebuilt..... Nor will DIRT have anything to do with Exchange/AD/MS configs. Consider the following:

Unity Server primary Member Server

Unity Server failover DC Server

(1) Unity Messanging server Member server

AD Global Catalog server (1U box in the rack)

This will help keep your VM AD domain in check. Because if you do not keep it in check, and AD falls apart for some reason... (seen it happen) you will not a replcation partner for AD. At least with the scenario above, you are covered.

You potentially could make the Exchange a DC and the Unity Failover a DC. All depends what TAC cares about to support.

hope this helps.