The contents of public folders are not replicated to other public folder stores in your organization automatically. If you want replication to occur, you must set it up manually, on a per-folder basis. You can configure each public folder individually to have replicas on multiple public folder stores. When you set up replication for a parent folder, its child folders are also replicated by default, although you can change this for individual child folders.
Public folder replication follows the multimaster replication model, in which every replica of a public folder is considered a master copy. In fact, there is no easy way to distinguish a replica from the original after replication occurs.
After you've decided which folders you want to replicate, you manually create and configure the replicas. The method for doing this involves pushing replicas from one public folder store to other public folder stores, using the property sheet of the public folder that you want to replicate. To set up replication for a public folder, open its property sheet in Exchange System and then switch to the Replication tab (Figure 10-16).
This tab lists any public stores that already contain a replica of the public folder. Click the Add button to open a dialog box that lists the available public stores in your organization that do not have replicas of the folder. Select the store to which you want to replicate the folder and click OK. The public store is added to the list of stores that contain replicas.
Below the list of public folder stores, you'll find a drop-down menu named Public Folder To Replicate. Use this menu to schedule the replication of the public folder to the other public folder stores. You have several options here:
Other options on the Replication tab let you see the last replication message Exchange Server generated regarding the current public folder and set the priority that replication messages concerning this folder should have in your Exchange system.
Figure 10-16. Configuring replication for an individual public folder.
Once you have created replicas of a public folder and configured how replication should behave at the folder level, you can also configure how replication should behave at the public folder store level. To do this, open the property sheet for the Public Folder Store object and switch to the Replication tab (Figure 10-17).
You can take two actions on this tab. The first is to configure replication defaults that apply to all of the folders in that store. You do this with a drop-down menu like the one used to configure a schedule for an individual folder, as described in the previous section. The value you specify here will apply to all of the folders in the store, unless you specify something other than the Use Default Schedule setting on an individual folder's property sheet. In other words, if you set a schedule for an individual folder, that schedule overrides the setting on this tab.
Figure 10-17. Configuring replication for an entire public folder store.
The second action you can take on the Replication tab for a public folder store's property sheet is to define limits for replication. By default, no limits are defined. If bandwidth between servers is a consideration, you can specify the maximum time, in minutes, that replication is allowed to go on when it occurs. You can also define the maximum size, in kilobytes, of a single replication message.
NOTE
When folders are replicated, conflicts are possible if users work with different replicas. Exchange has a way to handle replica conflicts intelligently and automatically. The Exchange server allocates revision numbers to all messages posted in a public folder. Using the assigned revision number, the server identifies conflicts as they occur. A conflict may occur when two revisions of the same message are sent from two separate servers to a single server during replication. The server places the conflicting revisions in the replica so that you can resolve the conflict yourself by integrating the revisions or, better yet, by having the authors of the messages work it out themselves. The server then replicates these revisions throughout the organization.
REAL WORLD Client AccessWhen a client requests a public folder, the request is processed by the closest Exchange server. If the server doesn't store the public folder or a replica of the public folder locally, the server queries the other servers in the routing group. If no servers in the routing group store the public folder, the server queries other routing groups. The configuration of the connector between routing groups determines whether or not it accepts such public folder referrals. The following connectors have the ability to refuse public folder referrals:
You can therefore configure these connectors to control which links in your routing topology handle public folder traffic. Connectors are discussed in further detail in Chapter 13.
- Routing Group
- SMTP
- X.400
- X.25