7.7 Managing Storage Groups

The Store process controls all of the storage groups that are active on a server. Exchange 5.5 uses a single client instance to the Store, used by the Store process to access the Private and Public Stores. Exchange 2000/2003 uses the client access mechanism to access the Store and Site Replication Services (SRS). However, these applications run in the context of separate processes, such as SRSMAIN.EXE, so they do not affect the Store. For Exchange, each storage group is a client instance running inside the Store process. As a separate instance, each storage group has its own set of transaction logs and checkpoint files.

The basic architectural concepts set down for the Store, including the atomic transaction model, logging, pointers, and use counts, are still valid for multiple storage groups. Operating multiple databases brings its own set of challenges, and we have to expand the established concepts to incorporate how storage groups work.

Figure 7.17 illustrates how storage groups help to make the current version of Exchange more resilient than earlier versions. Two storage groups are active on our sample server. If a problem affects the disk holding the EDB4 database, then you must take Storage Group 2 offline to fix the problem. Storage Group 1 remains active, and users whose mailboxes are located in any of the databases in Storage Group 1 will not be aware that a problem has occurred. You must take a complete storage group offline to fix a...