Exchange Queue & A: Site Resiliency with SCR, Recommended Root Volume Size, and More

You ask, Henrik Walther answers. Here’s what’s covered in this issue.

Q I'm currently architecting an Exchange Server 2007-based messaging infrastructure for a large enterprise requiring that the solution include site resiliency. So I'm considering deploying cluster continuous replication (CCR)-based Mailbox servers on Windows Server 2008 failover clusters with the active node in the primary (active) datacenter and the passive node in the secondary (backup) datacenter.

The datacenters are on different subnets but belong to the same Active Directory site, which means this is a supported scenario when installing­ the CCR-based Mailbox servers on Win­dows Server 2008. Would you recommend deploying CCR-based Mailbox servers in a multi-subnet environment?

Q Our organization consists of multiple physical sites spread across the U.S. as well as Europe, the Middle East, and Africa. Today all user mailboxes are hosted on Mailbox servers deployed locally at each physical site, but we want to consolidate those servers to one datacenter located in the U.S. Given this plan, can you tell us the maximum latency for Outlook 2003/2007 clients running in cached mode?

Q We have just deployed Exchange 2007 SP1 in our organization. The Active Directory topology consists of two sites. In the first site, we have deployed a CCR-based Mailbox server and two servers each with the Hub Transport and Client Access server roles installed. In the second site, we have deployed a single copy cluster (SCC)-based Mailbox server and two servers with the Hub Transport and Client Access server roles just as in the first Active Directory site.

The majority of clients in each Active Directory site still run Outlook 2003, which means a public folder store is required for free/busy information and the offline address book (public folders will be used only for this purpose, not as a data repository). Our initial plan was to mount a public folder store on both the CCR- and the SCC-based Mailbox servers so public folder changes could be replicated between the Active Directory sites. But then we heard that Microsoft doesn't recommend having­ more than one public folder store in an Exchange organization if one is hosted on a CCR-based Mailbox server, because public folder replication and CCR replication don't behave well together.

So with all of this in mind, what would you recommend that we do? We don't want to go down a path not recommended by Microsoft. But at the same time, we don't want Outlook 2003 clients on each Active Directory site to contact the public folder store on the other Active Directory site.

Q We are currently planning the storage layout for the Mailbox servers that will be part of the Exchange 2007 messaging environment we plan to transition to within the next six months. Since our enterprise consists of thousands of users, we plan to have 48 storage groups on each Mailbox server, all of which will be based on CCR technology.

Because of the number of storage groups, we will, of course, make use of mount points. Since we will create a mount point for each LUN on each of the CCR-based Mailbox servers, we are interested in hearing what the recommended minimum size is for the anchor drives where the mount points will be created.

Q Our organization's messaging infrastructure is based on Exchange 2007 SP1. All Exchange 2007 servers are located in the same datacenter and are based on CCR clustering technology, so we have local redundancy. But we have just set up a second datacenter to act as the backup in case our primary datacenter is lost during a disaster.

For Exchange, we want to deliver site resiliency by deploying one Hub Transport, one Client Access, and one Mailbox server in the backup datacenter. We then want to enable SCR from the CCR-based Mailbox servers in the primary datacenter to the Mailbox server in the backup datacenter. Before we start to build the Exchange 2007 servers in the backup datacenter, we have a question we hope you can answer. We want to know whether it's supported to enable SCR between SCR sources consisting of CCR-based Mailbox servers and an SCR target consisting of a standalone Mailbox server. And if this is the case, would you recommend that we follow this approach?