Exhchange Hub transport fialover

Hi All,

As you may have seen by previous posts we are working to provide an HA exchange solution. We have decided that the best way seems to be with the cloud solution mimecast. However they have a 3rd party system that requires a hub transport to work. We therefore need a fail-over hub transport onsite to ensure continuity in the even of hardware failure.

Can anybody advise on the steps needed to set-up a hub transport fail over?

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Will SzymkowskiConnect With a Mentor Senior Solution ArchitectCommented:
If you are only trying to have HA for Hub transport I would only install this single role on this server. If you install the CAS role on this server it will work but now you need to setup load balancing for CAS. If you do not setup load balancing for CAS both of your servers are now dependant on each other "at the CAS level".

Meaning if you lose one of your servers your HT role will be fine but you will have issues with ActiveSync, OWA etc. This happens because when you add any role for Exchange it gets registeered in Active Directory (ADSIedit).

This is where users will look to fine the CAS servers available, If they are not in a load balancing scenario users will try and authenticate to either one of the CAS boxes, which means some will work and some will fail/error out (because 1 of the CAS boxes are offline)

It is a good practice to have CAS/HUB on the same server for EX10 but you need to setup load balancing for CAS, either using one of the 3 options below..

- Hardware load balancer
- DNS Load Balancing
- Window Network Load Balancing

Hardware Load Balancing is the recommended way.
Will SzymkowskiSenior Solution ArchitectCommented:
If you are referring to HA for hub transport resiliency adding 2+ HUB servers in a single site creates HA for this particular role. Note that these servers will work together and in the event that 1 fails the other one will pick up the load.


unrealone1Author Commented:
Hi Will,

What is the process involved for getting that setup?
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There's no specific process, you install one Hub Transport role on 1 server, you install another Hub Transport Role on another Exchange server. Each server will automatically detect each and will work hand in hand, without any additional configuration.
Will SzymkowskiSenior Solution ArchitectCommented:
Yes that is correct, Hub transprot roles require 2 or more in order to be HA. (this is per SITE). So if you have multiple sites that host exchange (probably not due to using mimecast) but if you do, then you will need to add an additional Hub-T role in your second site.
unrealone1Author Commented:
So we have full exchange 2010 in-house at the moment.

If we just install another server with full exchange will it work off the bat or is there configuring to do with CAS to be done?
For the Hub Transport, no configuration extra.

For Load Balancing the CAS servers, with All roles installed on each server

Without a DAG.. you can set up a Windows NLB for the CAS Array.
With a DAG..you must use a load balancer such as an additional appliance or hardware load balancer and set up a cas array.

Here's some details on how to set up the CAS Array: http://blogs.technet.com/b/ucedsg/archive/2009/12/06/how-to-setup-an-exchange-2010-cas-array-to-load-balance-mapi.aspx
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