Tom,

Thanks for your response just to confirm we can have just one exchange cluster to install all (3) Unity servers but we need separate accounts for each Unity server.

FYI..this is not going to be geographically separated it is all in one campus.

Thanks Again,

Balu

If all the Unity servers are in the same room or campus, then (1) Exchange Cluster is fine. Just scale your Exchange Cluster and Active Directory to service 15000 accounts. Typically, if you are using Voicemail only, plan on putting in (2) Active Directory Domain Controllers. This will create backup copies of AD and also help with AD directory information requests from Exchange, etc.

Since the Unity servers in the same domain, there is no need to have multiple service accounts. Just create the accounts ONCE, then re-use these accounts for the next (2) Unity installs.

Digital Networking is optional between these three servers, but fairly easy to do since it is all one site, etc.

Tom,

Thanks.. I will talk to customer about having two DC's that brings up another question can we install AD,DC and exchange server in one box(even though MSFT doesn't recommend that)?

So I can get away with two servers for AD,DC and Exchange and 3+3 servers for Unity.

Even with this we have 8 servers already!!

You also mentioned Digital networking is optional, how Unity servers will talk to each other then or how subscriber in Unity A will talk to Unity C ?

Thanks again for your help.

You can put it all on box, the problem is that if that box goes out, you lose all AD information, and trying to rebuild AD and Exchange on box is going to be tough. That is why we typically recommend adding a DC just for AD replication. (and taking the load of the exchange server)

With 15K and VMO, you have to have about 8 servers. You can get away with probably (3) unity, (1) Exchange server, that is pretty risky with that many subscribers.

With digital networking, subscribers can forward and or send voice mail messages to other subscribers on all (3) unity servers. This helps with the directory. If you call the Directory Handle, it will know how to connect the caller to any subscriber from all (3) Unity servers.

Check out the Unity Guide, it's really good at describing this.

I guess I have to go with 9 servers if they want redundancy every where with 1 AD, 2 DC with exchange (cluster) and 3+3 unity servers.

Thanks again for your help.

I just did a visio for 15k also for a client.

(3) Unity servers

(3) Failover servers

(2) Exchange servers clustered

(2) Domain controllers

I maxed out the ports in the design also at 144 per server just to be safe.

Wow ...so we need 10 servers total!!

Thank you so much for your help..

I have a clear picture now.

I have one more question in the same scenario customer has a remote site with 300 users on a Gig link and they want a separate Unity cluster there.I was planning to add a server for DC/Exchange and Unity cluster servers at the remote site.

So now Main Site will have two DC servers and 2 servers for Exchange cluster and 3 pair of Unity servers and Remote Site will have a DC/exchange and pair of Unity servers.

Now my question is

1. If we have Exchange cluster at main site can we still add another Exchange server at remote site as part of the same exchange domain/routing group.

2. How many Unity servers we can do Digital Networking ?Is there any limitation for number of Unity servers?

I think there is a limit on the how many Unity servers, but it's hard to hit it.

Ideally, Unity and Exchange so be located on the same LAN. But since you have a GIG link between sites, it's basically the same thing. Just make sure you have >10ms roundtrip times or minimal latency.

Typically, the site is huge, and has certain business requirements, we will add an Exchange an DC server out at a remote site. But this is for voicemail only. Then do Sites and Services in AD to create the sites, and MTA for Exchange. If you have a GIG link with 300 people, there really is no need to have a separate Unity server out at the remote site. You have plenty of bandwidth, minimal users, etc. I would say the breaking point is 500, but that is your call.

Yes, you can still add another Exchange server to the Exchange Org. No problem. Just follow the MFST guidelines and you are set. (adding new Exchange server to the Org.

If you add the Exchange server, just remember to setup Sites and Services for Message Transfer Agent (MTA)

Cheers!

As usual you were really quick on responding I really appreciate that.

Customer wants a Unity and Exchange server because these sites are 150 miles apart and Fiber has been cut couple of times in last 3 months and they don't want these users left without VM. This site has potential to grow more than 500 users by next year.

Sorry to go back again on Exchange so if we built the Exchange as Cluster at Main site we can still add a Exchange server at remote site correct?? in other words since exchg is built as Exchg Cluster will that affect anything on adding a exchg server at remote site.

One more thing does it have to be less than 10 ms for RTT?

Again thank you so much for your help.

So if the users are left without voicemail, does the router onsite have SRST? Because you can program the SRST router to roll the call after 4 rings back out the local PSTN, and into the datacenter where Unity resides. The voicemail will be there waiting for them then. The MWI lights may be out of sync for 24 hours or until the next sync, but big deal. Fiber was cut right?

>10ms on any LAN is ideal for connectivity.

Think the Exchange Cluster as (1) Exchange server in the Exchange Org. If you add other servers, it will it be listed in the Exchange Org.

Cluster1

Store1

Store2

Store3

ExchangeSiteA

Store1

Since there are lot of potential for growth they have a SUB CM there at remote site.

Since Unity servers can operate with minimum features when they lost connection to partner exchange server I might give that option also to customer to go without Exchange because that should cover VM.

Thank you so much for your help.

Right, Unity at the site without Exchange can still take messages, hold them, but no retrieval, until the Message store (your Exchange cluster) is back online or fiber is back up. CallHandlers maybe crucial to in the design. This is another reason I put Unity at the remote site.

Cheers!