Beginning the restore and copying the databases |
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By Jerry Cochran
01 Nov 2004 | SearchExchange.com |
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The following is tip #13 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.
By reading the beginning of the backup set, the backup application gets a list of databases
that are available. Once the administrator selects the correct database to be recovered, the
backup application begins by making ESE API calls to start the restore.
First, the backup application asks the administrator for inputs, such as the server to
restore to, the location and a temporary directory for the log, patch (if applicable) and
restore.env files.
The backup application makes the HrESERestoreOpen call to gather this information and
then the HrESERestoreAddDatabase call once for each database that is going to be
restored. At this point, ESE leaves it to the backup application to restore the needed
database files to the proper locations. ESE does not get involved much in copying the
database files to disk from the backup set. ESE allows the backup application to make Win32
file system calls directly to the operating system and copy the files.
The reason for ESE's lack of involvement is based on the reasoning that the database files
have already been checksummed when they were backed up, and if the backup set is complete,
the databases should be intact. There is no reason for ESE to check the database integrity
when it is being restored. Since the databases being restored are dismounted (i.e., not open
files), it is much simpler and faster to have the backup application copy these files directly
to disk.
Get more "20 tips on protecting and recovering Exchange data in 20 minutes". Return
to the main
page.
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).
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