Exchange Server 2007 : Deploying a Cluster Continuous Replication Mailbox Cluster (part 1)

Deployment of a Cluster Continuous Replication (CCR) mailbox cluster is a fairly straightforward process but it does have several steps that must occur in the correct order. By becoming familiar with the requirements and the process, the implementation should be fairly uneventful.

Be aware that a two-node CCR now supports the concept of a file share witness to act as the local quorum. This means that rather than using a shared drive to track the status of the cluster, this function is performed on a file share to which both nodes have access. This is a useful change because in the past, you needed at least three nodes in a cluster to utilize a majority node set (MNS) quorum. By using the file share witness, you can run with only two nodes and not be at risk of split brain syndrome, where the two nodes each believe they should own the cluster resources.

Requirements for CCR

You will need two servers that are capable of supporting the Exchange Server 2007 Mailbox role. You don’t need shared storage with a CCR because the transactions are shipped to the passive node and applied locally. This results in two independent databases and sets of log files on two different servers with independent media. You will want to follow the same standards as you would with a normal Mailbox server in terms of database sizes, separation of logs, and databases and hardware specifications to support your anticipated user load.

To set up a CCR, you need the following:

• Two servers running Windows Server 2003, Enterprise Edition

• Two network interfaces per server

• Three hard drives per server (OS/Logs/Databases)

• Hotfix 921181—support for file share witness

Hotfix 921181 can be downloaded from http://www.microsoft.com/downloads/details.aspx?familyid=C62E21D9-192C-44DD-9C80-403BDA97990C&displaylang=en

You will also need to create the file share that will be used as the file share witness by the cluster. It is recommended that you place this file share on the local Hub Transport server.

Preparing the Operating System

The CCR mailbox cluster is based on a Windows Server 2003 cluster with Exchange Server 2007 running on both nodes. To prepare those nodes to participate in a Windows cluster, perform the following items on each node:

When this process has been completed on both nodes, the systems are ready for the rest of the configuration process to continue.

Creating the File Witness Share

The file witness share is the replacement for a shared quorum drive that allows a two-node majority node set cluster to operate without suffering from split brain syndrome, where the cluster is split into two or more partitions that cannot communicate with each other. The quorum is used to guarantee that any cluster resource is brought online on only one node. To create this share, follow these steps:

This creates the share with the correct permissions for the cluster to later utilize it for the file share witness.

Creating the Cluster

Now that the nodes are prepared and the file witness share is created, the cluster can be created. Be sure to have the following items ready for the cluster configuration:

• Unique names for each node

• Unique name for the cluster identity

• Unique name for the Exchange virtual server

• Unique IP addresses for each of the names created previously

With these items ready, complete the following steps to create the cluster:

1.	From the Start menu, click Program Files, Administrative Tools, Cluster Administrator.
2.	Under Action, choose Create New Cluster, and click OK.
3.	The New Server Cluster Wizard launches. Click Next.
4.	Choose the domain that will host the cluster in the drop-down menu, and then enter the name of the cluster. This is the name of the cluster itself and doesn’t affect the Exchange virtual name. Click Next.
5.	Enter the name of the first node that will participate in the cluster. Click Next.
6.	The New Server Cluster Wizard analyzes the node to see if it can become a cluster node. A warning appears about the lack of a shared quorum device. Disregard this message as you will be using a majority node set quorum. Click Next.
7.	Enter the IP address that will be used to manage the cluster. This needs to be a unique and reachable IP address. Click Next.
8.	Enter the name and password of the account under which the cluster service will run. This account needs to have local Administrator rights to each node of the cluster. Click Next.
9.	At the Proposed Cluster Configuration screen, click Quorum, and change the option to Majority Node Set via the drop-down options, as shown in Figure 1. Click OK and then click Next. Figure 1. Setting the Quorum type.
10.	When the New Server Cluster Wizard completes its tasks, click Next and then click Finish.