The following is tip #1 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 backup and restore functions of Exchange's ESE provide three types of backup capabilities: full, incremental and differential. Combined with Windows Server 2003's VSS, Exchange Server 2003 also supports snapshot backup types (more on this type of backup later).
A full backup (also called a normal backup) backs up the entire directory or information store and allows you to restore it from a single backup. An incremental backup backs up just the changes since the last full or incremental backup. These are simply the transaction logs that have accumulated since the last full backup. Restoring incremental backups requires the original full backup plus all the incremental backups (transaction logs) made since that time. A differential backup backs up the changes since the last full backup. Restoring a differential backup requires one differential backup and the original full backup. Appendix A provides pointers to backup and restore API functions and their specifc uses.
On-line backup operations are fundamental to Exchange Server and enable you to back up databases without shutting down the entire server to perform a file-by-file type backup (off-line backup). While backup operations are in progress, all services continue to operate, and users can access their data on the Exchange server. Database pages that are cached in memory in the information store buffer pool continue to be updated and pushed to the database on disk. Transactions also continue to be written to the transaction log files, and the checkpoint file continues to advance. All in all, the backup and restore technology for Exchange 2000/2003 is very similar to previous versions of Exchange Server with one notable exception. Exchange 2000's advent of multiple storage groups and multiple databases
|Table 5.1 Exchange Server 2003 Backup Types Backup Type||Files Included||Logs Truncated?||Restore Method|
|Normal (Full)||Database (EDB+STM) files, Log files, and Patch files (for Exchange 2000 SP1 and earlier versions)||Yes||Last normal backup|
|Incremental||Log files only||Yes||Last normal + all incremental backups|
|Differential||Log files only||No||Last normal + last differential|
|Copy||Database (EDB+STM) files, Log files, and Patch files (for Exchange 2000 SP1 and earlier versions)||No||Not applicable|
|Snapshot (Windows VSS)||Special (more on this type of backup in later in the chapter)||Special*||Special*|
(MDBs) has a substantial impact on how the Exchange backup API works. Table 5.1 compares the backup types available for Exchange 2003.
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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).