IBM DS6000, DS8000 Consistency Checks on Excha nge Database and Log Files, Best Practices for Exchange Storage and VSS Backups

Exchange 2003 VSS Backup Solution
For IBM Storage DS8000/DS6000
And Symantec Backup Exec 11d
Page 72 David West, David Hartman
©Copyright IBM Corp. 2007
Consistency Checks on Exchange Database and Log Files
For an Exchange VSS backup, Microsoft requires that each database file
(.edb, but not .stm) and each transaction log file required for the restore have
a checksum consistency check run against the files. This consistency check
is accomplished by running eseutil.exe with the proper options against the
files which exist on the snapshot. For offhost backups, the consistency
checks are run on the offhost server rather than on the Exchange Server. Off-
loading the consistency check is recommended to further reduce the backup
impact on production Exchange servers.
If any of the files fail the consistency check, the entire backup will fail, the
backup image will be discarded, and the Exchange VSS Writer will be notified
of the failure. When this occurs, Exchange will not truncate log files.
Failure of the consistency check may be an indication of either database
corruption or a problem with the snapshot. The Exchange administrator
should investigate the reason for the failure by dismounting the Exchange
database which caused the failure, and running eseutil.exe against the
database file to determine the cause of the corruption.
Best Practices for Exchange Storage and VSS Backups
The following are recommended configurations to prepare the Exchange
environment for Backup Exec VSS operations.
• The volume(s) which contains the Exchange databases and log files
should be dedicated to Exchange only. Other types of databases (e.g.,
SQL) should not reside on the volume(s). Only Exchange objects will
be included in a snapshot backup.
• Disable circular logging for all Exchange Storage Groups.
• Transaction logs should reside on a different volume than where the
Information Store resides.
• If you are running the integrity check, ESEUTIL throttling minimizes the
impact on production LUNS during the VSS copy-on-write process.
Although the current version of Backup Exec does not provide
throttling, this is planned for a future release. It is also recommended to
use the offhost feature to further minimize performance impacts.
• If you are planning on restoring individual mailbox messages or folders,
you should ensure the backups are to disk, rather than tape. Granular
restores from tape require staging of the data from tape to disk first,
which impacts the restore times and the ability to meet SLA times.