The following is tip #7 from "20 tips on protecting and recovering Exchange data in 20 minutes," excerpted from the book, "Mission Critical Microsoft Exchange 2003" (Digital Press, a division of Elsevier, Copyright 2004). For more information about this book and other computing titles, please click here. Return to the main page for more tips on this topic.
The next step in the process involves backing up the database files.
ESE gets the list of storage groups and databases to be backed up from the backup application via the backup APIs (HrESEBackupSetup). The backup application makes three API calls to backup the databases. HrESEBackupOpenFile opens the database file for reading, HrESEBackupReadFile reads the database, and HrESEBackupCloseFile closes the database when all the pages have been read. These databases are not simply copied to the backup set because they are open files (remember Exchange backups allow the databases to be back up on-line). Instead, ESE begins to send the backup application 64KB chunks (16 4-KB pages at a time) of database pages in sequential order. This is also the crucial step where each page is checksummed and an error results in the backup operation terminating with a -- 1018 (the HrESEBackupReadFile is the API call that initiates checksumming operations for database, log and patch files during the backup operation). ESE will continue this process until all pages for each database are sent to the backup application.
Also remember that Exchange 2000/2003 supports two database files -- the Property Store (EDB) and the Streaming Store (STM). Both database files are read page-by-page by ESE and sent to the backup application to store as part of the backup set. ESE will perform these operations for each database being backed up.
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About the author: Jerry Cochran is a contributing editor for Windows IT Pro and Exchange & Outlook Administrator and a group program manager for Microsoft. He is the author of Mission-Critical Microsoft Exchange 2000 (Digital Press).