Registry Settings
Exchange wouldn't be Exchange without some registry settings that you can twiddle to change the way things work. Background maintenance has a selection for you to experiment with, if you like playing with fire. You should reset these values only if you have an extremely good reason to do so.
All the registry values are of the REG_DWORD type. They fit into three registry subkeys, as Table 2 shows, where PS indicates the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\ParametersSystem subkey, M indicates a subkey for a mailbox store, and P indicates a subkey for a public store. In versions earlier than Exchange 2000, Microsoft placed all the general registry settings for the Store in the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeISParametersSystem subkey, but because Exchange 2003 and Exchange 2000 support Store partitioning, we now have a subkey for each server with separate subkeys for each store under that server. Web Figure 4 shows the registry hierarchy and settings that govern how the Store deals with a public store on an Exchange 2003 server.
Tracking Background Maintenance
As with any other operation in Exchange, the selected level of diagnostic logging determines how much information the Store writes about maintenance operations into the Application log. You set the level for diagnostic logging by selecting a server in ESM, opening its properties dialog box, and going to the Diagnostic Logging tab, which Web Figure 5shows. To log sufficient details about background maintenance events, you need to adjust the Background Cleanup setting for the MSExchangeIS Public Folder and Mailbox objects from its default logging level of None to Minimum, Medium, or Maximum. I recommend the Maximum setting for background maintenance; it doesn't generate a flood of events (unlike the settings for other features such as public folder replication), and you can always learn something from the extra detail generated at this level. After you're familiar with the different operations and know what to expect, you can reduce the setting back to Minimum.
After you apply the new setting, the Store begins to generate events the next time it runs background maintenance. Table 3, page 13, lists the most common events that you'll see. Except on very large or heavily loaded servers, many of the tasks are completed quickly. The obvious exception is background defragmentation. This intense activity can take many hours, depending on background load, server capacity, and the amount of data to process.
Exchange uses some sophisticated database technology to deliver its rich functionality set to clients. Behind the scenes, the Store does a lot of processing to keep everything aligned and in good shape. Most of the Store's work is automatic and doesn't require administrator intervention, but it's good to know what's going on in the background, just in case.