Hi everybody, I will be going through the process of implementing 2 x Exchange 2010 Enterprise servers and migrating things over from our Exchange 2003 server. I have a few questions though i would like to ask you all about. Facts of our current setup: - 1 x front end server for OWA - 1 x back end server for the rest - 400 users - 950+ mailboxes - 708 GB mail across 5 MB stores and 15 databases. My questions really relay to OWA, , ECP, CAS ARRAY and DAG. I was thinking to install CAS, HUB and MB on both servers. Both servers will be in our data centre. * If one server goes down, will clients use the other CAS automatically or is a CAS array needed? * I want to use OWA and ECP, but does this needs to be installed and configured on both servers? again i am thinking if one server goes down, let the other one take over. * I think i want to split the active users between the servers on each MB server role and then have copies on each server in case of one of them goes down. Any help is greatly appreciated. Ronnie

Maybe this How to move from a Single Server to High Availability with DAG primer will help from MSExchange.org: http://www.msexchange.org/articles_tutorials/exchange-server-2010/management-administration/how-move-single-server-high-availability-dag.html Also I believe in order to make CAS redundant you need to install and configure the Network Load Balancing Cluster feature of the OS. The CAS and HUB roles use that, where as the Mailbox role uses the Failover Cluster feature. I am not sure if you can run both Cluster types on one box, maybe someone can confirm that for us, but I think you can.

I am still not quite sure how it all works when i have 2 servers in one site. Do i understand this correctly that is i install CAS, HUB and MB on each server, the HUB roles will load balance each other without any further work. With CAS role installed on both servers, would i need a CAS array to load balance the 2? if i dont create a CAS array, then i take it if one server goes down you have to go to the other manually? Also from external access point of view, you would configure your external DNS to look for the CAS array? Do i need a DAG in order to have database copies? I seem to remember that you are able to create a database copy on a different MB server without the need of a DAG Regards R

To sumup, you need both CAS array with NLB (or HLB) and DAG so that if one server goes down, clients can auto-switch to another server. Since DAG cannot setup on a server that is actting as NLB member, you should use HLB if you have only two servers. Or you may consider virtualization such as Hyper-V or Vmware. Refer to: http://technet.microsoft.com/en-us/magazine/ff626260.aspx Fiona Liao TechNet Community Support Hi Fiona and Konrad, We are actually using VMware with everything sitting on a Fibre Channel San. Both of our new exchange 2010 servers will sit in our datacentre. You say i may should consider virtualization, could you please elaborate on this? have a missed something important in my idea for the design? My initial thinking was to have a much HA as possible so i can make sure that we are covered from a hardware or software failure. Obviously on the VMware side of things we are covered on the hardware side. but i want to make sure that OWA is always up, if a DB becomes corrupt or something that there is a copy of it. Could you comment on my design idea? 2 Exchange 2010 enterprise servers. on VMware with vmotion and disaster recovery enabled. Ronnie