Hi Exchange Expert,

We have in premises exchange server running 2010 SP1. Our Exchange Infra is as below. all of the servers below are in the form of Hyper V VM. so, there are 2 physical server and each of them hosting AD, Transport, and Mailbox.

1. 2x Server 2008 R2 AD for redundancy (for instance: Ad01, Ad02)

2. 2x Exchange Transport Server for redundancy (for instance: Tr01, Tr02)

3. 2x Exchange Mailbox Server for redundancy (for instance: mb01, mb02)

For transport server, we actually implement a cluster using the network load balancing manager, so it could load balance. the name of the cluster is Trcluster, which has two members inside, Tr01 and Tr02.

We have also implement DAG for the the database, mb01 and mb02. so mb01 has the copy of mb02 in the server and vice versa. Beside, we also include 2 members at the remote site servers. this remote site servers also has the transport cluster of RemoteTrCluster, with the members: RemoteTr01, RemoteTr02.

However, now one of the physical server containing the Ad02, Tr02, and Mb02 is down. One thing that we don't understand is how come the exchange transport is not able to failover since we have cluster here. it is failed to run. The database is able to failover, but the transport is not running using the Trcluster. So what we do is to failover the database to remote exchange server and then the exchange transport is able to run using the RemoteTrCluster.

Please give any advise of what is going on in our Exchange infra.

Thanks.

Regards,

Please define what you mean by "doesn't failover"?  If you're talking about outbound mail, it doesn't use load balancing.  Simply remove the failed server from the send connector(s) and after a short while it'll all get requeued through the working servers.

You didn't ask, but I usually don't load-balance SMTP for transport since SMTP servers handle failures pretty well on their own.  If you have two transport servers, you can give each of them its own Internet IP address and create two MX records for inbound mail.  Sending SMTP servers will manage to get the mail to the server that's up.  Generally the only need to load-balance SMTP is for client connections, which are not as smart.

Hi Ed,

Thanks for your reply.

Sorry maybe I didn't get the term of "failover" right. The "Failover" is supposed more accurate when referring to the mailbox database.

We have two transport server, Tr01 and Tr02. both of these are the member of the cluster TrCluster. So, the outlook server setting will be "trcluster.domain.com" instead of Tr01.domain.com or Tr02.domain.com. Now, the question is: why when the physical server that contain one of the transport server (e.g Tr02) and mailbox server (e.g mb02) VM is down, the email queue will get stuck. I thought it supposed that, in the cluster, if the Tr01 is down, then Tr02 will take over for the transport as both of them are member of the TrCluster.

The issue is only resolved, when we failover the mailbox database to the remote exchange server, whereby the remote exchange server also has its own transport cluster called "RemoteTrCluster".

Please advise.

Thanks.

TrCluster is a failover cluster or an NLB cluster?

What queue gets stuck?

FYI, "failover" happens on its own, such as when one node fails.  When you initiate it, it's a "switchover".

Hi Henry,

Thanks for your response. It's great to hear the good news. Besides, "when we failover the mailbox database to the remote exchange server", it is a switchover.

Hope this can be helpful to you.

Best regards,

Hi Henry,

As Ed said, I guess its a NLB cluster for your CAS roles or at most for inbound SMTP connections for Transport.

You didn't mention about them(CAS), where are they; hope they are co-located with the Hub Transport.

Resiliency was designed into the Hub Transport role so that Hub Transport server to Hub Transport server communication inside an organization automatically load balances between available Hub Transport servers in an Active Directory site. In order to load balance inbound SMTP connections from external SMTP servers/clients, internal LOB application, and devices such as miscellaneous network devices you could use WNLB or a load balancer solution from a 3rd party vendor.

TrCluster is a failover cluster or an NLB cluster?

What queue gets stuck?

FYI, "failover" happens on its own, such as when one node fails.  When you initiate it, it's a "switchover&

Hi Henry,

Hope you have tried to restarting the transport service...and verified.. the queue is still not flowing after switchover.

Hi Henry,

Hope you have tried to restarting the transport service...and verified.. the queue is still not flowing after switc

Is there a mailbox server?

Again, I've been trying to tell you that NLB doesn't figure into outbound SMTP at all.  What's more important is where the outbound mail goes, is it to a smart host or DNS routing?  If you're using one of the normally recommended two-NIC configurations for NLB, then you'll want to make sure that all IP addresses of the NLB cluster are allowed to send outbound through the firewall or to your smart host.

Hi Henry,

Normally I have seen CAS+HT, MBX alone or all combined into one. But in your case it appears to be HT,CAS+MBX.

I would like to know, how did you comeup with WNLB for the HUB transport. I don't  really think that works(You might be messing up the Exchange's internal logic).

But I do know that Exchange's inbuilt HA for HT without NLB works just fine as Ed said earlier.

SMTP failover:- The Load-Balancing in most cases is used to Load-Balanced incoming or outgoing emails from External source. And that too using HW NLB .

Here are some more info on Hub Transport Load-Balancing:

Deployment Options for Hub Transport Servers

You cannot install the Hub Transport server role on a server that is configured as part of a cluster(for something non-Exchage related I guess).

Configure Windows Network Load Balancing for Hub Transport Servers

You can configure Windows Network Load Balancing (NLB) to distribute non-Exchange messages among your Hub Transport or Edge Transport servers.

This topic is archived. No further replies will be accepted.

Other recent topics

Remote Administration For Windows. Easy remote access of Windows 7, XP, 2008, 2000, and Vista Computers

Click here to find out more

Reboot Hundreds of computers, disable flash drives, deploy power managements settings.

Click here to get your free copy of Network Administrator. Over 25 plugins to make your life easier