How an Exchange Server Stores Data
Exchange servers store data as two separate files:
- an .edb file
- an .stm file
Together, the .edb file and the .stm file form an Exchange store repository. The .edb and .stm files function as a pair, and the database signature (a 32-bit random number combined with the time that the database was created) is stored as a header in both files. The internal schema for the .stm pages is stored in the .edb file. It is important to understand that a single database in the Exchange Server Information Store service contains two files, the .edb file and the .stm file. One of these files is of little use without the other file. The traditional .edb file and its accompanying .stm file are a single unit.
The .edb file contains many tables that hold metadata for all e-mail messages and other items in the Exchange store, in addition to the contents of MAPI messages. The .edb file is an ESE database, and because it is used primarily to store MAPI messages and attachments, it is also referred to as the MAPI-based database.
The .stm file, in contrast, stores native Internet content. Because Internet content is written in native format, there isn’t a need to convert messages and other items to Exchange format. The .stm file is also an ESE database, referred to as the streaming database.
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