Hi All, We have Exchange 2007 CCR accross 2 Data Centres via a AD Site / VLAN that span both Data Centres. When we move to Exchange 2010 - is there any benefit to keeping this streatched AD Site / VLAN ? I know Exchange 2010 does not require this but just thinking if there is any advantages in building Exchange 2010 on this SPANNED AD SITE or should I go for 2 AD Site / VLAN's now? Thanks ECL

I don't think that there is any benefit.Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."

Hi Ed, I did think that with 2 AD Sites - in the event of the Data Centre Site failover it may take longer for the clients to flush the DNS to pick up the IP's of the servers in the other site on a different subnet but if I am using Hardware Load Balancers it should not be a problem ?? Thanks ECL

Hi Ed, I did think that with 2 AD Sites - in the event of the Data Centre Site failover it may take longer for the clients to flush the DNS to pick up the IP's of the servers in the other site on a different subnet but if I am using Hardware Load Balancers it should not be a problem ?? Thanks ECL This is true, however there are often performance and security disadvantages to a stretched VLAN. In my experience these have outweighed the DNS latency benefit. BTW, setting the TTL to <5 min can help here. Mike Crowley Check out My Blog!

Hi Mike Do you think using Hardware Load Balancer will help? Talking to the network guy if I had VIP1 for Data Centre 1 and VIP2 for Data Centre 2 - they could setup each VIP to point to the other Sites VIP as backup? e.g. Have VIP1 with a secondary connection of VIP2. So on failover of Data Center 1 the clients will attempt to access VIP1 which will redirect them to VIP2 on Data Center2. Does the above sound like it would work? Thanks ECL

I can't say without knowing more about your infrastructure. In general, I prefer to have standby sites be standby and not service normal production requests. I recognize that's not always optimal cost-wise, but it generally results in fewer problems.Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."

Hi Ed, Not sure if this will work but what I am thinking of is; VIP1 - loadbalancer in Data Center1 to 6 Exchange CAS Servers VIP2 - loadbalancer in Data Center2 to 6 Exchange CAS Servers (DR) casarray.domain.com - Cisco GSS Global Site Selector (Primary points to VIP1 and Secondary VIP2) The GSS is basically a DNS server with intelligence built in to Check the services before offering the IP Address Outlook clients connect to casarray.domain.com to connect to the CAS which primary is VIP1 then when Data Center1 fails it swiches to VIP2 But just thinking now it looks like the clients will still have problem with the TTL on failover :) Thanks ECL

What you have to decide first is whether you want e-mail service to automatically fail over to the DR datacenter, and I think the issue behind that is much more around the mailbox role than it is the CAS role. If you are going to have six CAS servers at both datacenters, then I don't think you really need to worry about CAS failover between datacenters unless the mailbox role has failed. I should think that ig GSS finds that all CAS servers in the production datacenter are down and chooses to route everything to the DR datacenter, it will do so because the production datacenter is down (or it's network is down), and then you're failing over to CAS servers where your standby mailbox servers reside, so all is good. You really need to decide whether you think that the risk of things failing over when they shouldn't is something you can live with. I don't think necessarily it's a bad idea to force an administrator to make that call. With Exchange 2010, the risk of that happening isn't as great as with previous versions, but failovers aren't always completely clean.Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."

Thanks Ed

You're welcome. Happy to have helped.Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."