How to Rebuild Your Exchange Organization

No one is right all the time, not even highly paid external consultants who plan Exchange deployments. However, Exchange consultants need to get a deployment's organization design right the first time they plan it. Organization design is a major part of an Exchange project. The Exchange organization establishes how all of a deployment's servers communicate with one another. Deployment designers spend hours deciding how to group servers into sites, how to use different types of connectors to link sites, and how to build a corporate Directory that Exchange Server synchronizes among sites. After planners implement an organization design, making changes to fundamental parts of the organization becomes prohibitively difficult. For example, until recently changing the name of an organization required you to reinstall Exchange Server on all the organization's servers.

This difficulty of changing an organization creates problems even when organization planners make no mistakes. Administrators of networks with appropriate designs sometimes need to integrate two sites­for example, when they upgrade the bandwidth of intersite connections. Network availability, in terms of speed and quality, is an enormous influence on site design. I recommend connecting servers to form a site only when you can provide at least 128Kbps of bandwidth between all the servers. However, the fewer sites you have in an organization, the easier the organization generally is to administer. So if bandwidth between two existing sites increases, administrators might want to combine the sites.

Business developments can also impose stress on a messaging system. Consider the position of messaging administrators when their company acquires another company. Both companies might use Exchange Server, but they're unlikely to use the same name for their organizations. Merging multiple sites takes a huge amount of coordinated effort from all administrators involved, and such a merger can grind an internal messaging system to a halt.

Technology improves, business arrangements change, and network planners make mistakes. Expecting Exchange to be flexible enough to accommodate change seems reasonable. Microsoft has finally provided a tool to help you migrate servers from existing sites and merge Exchange sites. Microsoft's release of the Exchange Move Server Wizard (formerly code-named Pilgrim) makes rebuilding an Exchange organization more feasible than the task was previously. Moving servers from one organization to another still requires a lot of planning, but the wizard is the tool you need to perform the brain surgery.

Why Is Moving Servers Complicated?
Comparing the intersite migration of Exchange Server machines to brain surgery might seem extreme, but integrating two large Exchange sites requires a great deal of effort and attention to detail. To understand how complex the process is, think about how the Directory names objects.

The Directory allocates a unique distinguished name to all objects--­including servers and mailboxes--­within the Directory. Exchange ensures each object name's uniqueness by using the organization name as the root, so objects inherit their organization and site names as part of their distinguished name. Every object in the Directory has a root of

/o=<Organization Name>/ou=<Site Name>

Any change at an organizational or site level (such as moving a server from one site to another) requires you to change the distinguished name for every object associated with the move. You can't just drag a server from one site to another.

Examine the distinguished name of my server DBO-EXCHANGEIST, which Screen 1 shows. To view this information, I started Exchange Administrator in raw mode by appending the /r switch to admin.exe. I selected DBO-EXCHANGEIST and selected File, Raw Properties. The Obj-Dist-Name property contains the distinguished name. In Screen 1, Obj-Dist-Name is

/o=Digital Equipment Corporation/ou=Dublin/cn=Configuration/cn=Servers/cn=DBO-EXCHANGEIST

This distinguished name tells me that this server is in the Dublin site in the Digital Equipment Corporation Exchange organization.

To move this server to another site in the same organization, I would have to change the /ou=Dublin part of the distinguished name of all the objects that Exchange associates with the server, including mailboxes, public folders, and distribution lists. I would need to adjust the Directory's organizational information about the source and target sites so the source site knows that the server left it and the target site knows that the server joined it. This move would also affect the contents of the Information Store (IS) because Exchange Server stores message recipients' distinguished names alongside mailbox data. Finally, if I use intersite replication, I would need to make sure Exchange Server replicated all my changes to all the other servers in the organization.

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