A checksum error while creating a backup of MS Exchange database occurs when the checksum values in the page header do not match with the values returned by the ‘READ’ call. The reason for mismatch of the values is corruption of database due to anti-virus scanning, hard disk subsystem damage, and third-party programs. In such cases, the backup stops and the data saved in the database becomes inaccessible. To overcome such error messages and to access data, the user needs to restore database from online backup. However, in case, no online backup is available, then the user needs to opt for a commercial Exchange Repair application.

Consider a practical case, wherein you encounter the below error message while checking the progress of Veritas backup:

“Backup - \\FSNACORP\Microsoft Information Store\First Storage Group Access denied to  database Mailbox Store (FSNACORP). Database or database element is corrupt”

On checking the event viewer, you find the below event ID:

“Event ID:478 Source: ESE Information Store (4004) The streaming page read from the file "D:\Program  Files\Exchsrvr\mdbdata\priv1.stm" at offset 1267851264 (0x000000004b91e000) for 2445  (0x0000098d) bytes failed verification due to a page checksum mismatch.  The expected  checksum was 2928845483 (0xae92a2ab) and the actual checksum was 3806978948  (0xe2e9e384).  The read operation will fail with error -613 (0xfffffd9b).  If this  condition persists then please restore the database from a previous backup.”

Cause:

As described in the error message, Exchange database is corrupt.

Resolution:

To overcome the above error message:

  1. Uninstall all the anti-viruses and third-party software.

  2. Use a previous online backup to restore the information store.

  3. Move all the mailboxes in database to a new server or mailbox store.

  4. In case all the above measures fail to resolve your problem, you will have to repair the database using eseutil/p command. However, repairing the database using this command brings the database in unstable state. To avoid any such situation, it is recommended to repair your database using a third-party Exchange Server Repair application. Such MS Exchange Repair software ensure safe repair of corrupted databases without modifying the original database.

Exchange Server Repair Software is a safe EDB Repair application to repair logically damaged Exchange Server 5.5, 2000, 2003, and 2007 databases. The read only utility saves the mailboxes in a PST file format. It can be installed on Windows 7, Vista, XP, 2003, and 2000.