Setting up a DAG scenario between 2 sites Exchange 2010

http://www.msexchange.org/articles_tutorials/exchange-server-2010/high-availability-recovery/designing-site-resilient-exchange-2010-solution-part3.html

http://www.msexchange.org/articles_tutorials/exchange-server-2010/high-availability-recovery/uncovering-exchange-2010-database-availability-groups-dags-part2.html

Netexperts,

See the answer I've provided here: https://www.experts-exchange.com/questions/26550676/Exchange-2010-high-availability-Database-Availability-Groups-DAG-or-Vmware-HA.html

The answer contains information among 3 other accepted answers regarding, dag system design, dag network req and dag options (depending on which roles are installed + among other options)

Feel free to ask more questions if you are wondering about something,

cheers

Thanks,

Just as an overview then, i can create a VM with Exchange 2010 on each server (one at each site), add a second subnet to the second network card on each server, create a static VPN between both subnets on both servers (so 2 subnets with 2 VPN's between the 2 sites). Run the create DAG group commandlets and then manage and configure it through Active manager ?
Do i need more than one database for mail on each server ?

##Just as an overview then, i can create a VM with Exchange 2010 on each server (one at each site), add a second subnet to the second network card on each server, create a static VPN between both subnets on both servers (so 2 subnets with 2 VPN's between the 2 sites). Run the create DAG group commandlets and then manage and configure it through Active manager ?##

I have not tested this om vmware on two respective sites, thru two subnets. Though at the moment im setting an exchange environment close to the one your describing. But in practice you should be fine, but i Urge you to read the following regarding unicast vs multicast when using DAG on two virtualized exchange servers:
http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1556

Do i need more than one database for mail on each server ?
No you only need one database for mail on each server.


Netexperts,
One more thing, remember that if you have all the three roles installed on an exchange server (hub, cas and mailbox), and your planning on loadbalancing cas roles and cluster the mailbox databases.
You will not be able to do this with two exchange servers, with each holding the three roles because,
Cas roles uses windows network load balancing and dags (database availibity groups) uses windows built-in clustering feature,
these two enabled and installed on the same Windows server 2008 is not supported, this is by design from microsoft.

Only way you can make the above work is to use a hardware load balancer (which costs alot)

If you want this you will need to have two exchange servers with hub + cas and two exchange servers holding the mailbox role.


Another thing that you can, which actually is not a "load balance", is to use DNS round robin.


cheers

That's great.

I don't think i need any load balancer (unless i have misunderstood) as i just want all users to use the one server for mail and then for it all to failover to the second if it goes down.

You simply want everything to failover to the other server if the first one goes down,

For the mailbox failover, implementing dag is fine. Though remember for the second exchange to "take" over the other services and functionality, you should design this a bit more, for example giving the second exchange server its on public ip address and configure your MX records properly on your external DNS

That's fine. We have enough public IP's so we can set the 'primary' Exchange server a lower MX score than the other on the external DNS. I take it the second subnet would be used for a kind of heartbeat purpose then and the mailboxes would be replicated from the primary Exchange server to the second automatically for if it fails over ?

That's great,

Many Thanks