Monday, 12 October 2015

How to Fix Cyclic Redundancy Check (CRC) Error of Exchange Backup File

Exchange BKF files are meant to assure us that our important Exchange data is safe, in case any disaster strikes. These BKF files may prove out to be very handy in situations where admin has lost access of Exchange as data could be easily recovered from Exchange BKF File whenever needed.
However it may happen that your Exchange BKF file got corrupt due to any possible reason such as Cyclic Redundancy Check (CRC Errors), Interruption during backup, Deletion of Windows partition storage media, Software/Hardware Malfunctioning, Virus Attack or due to Corrupt Storage device. From all these reasons above CRC error is the most common cause.

Here in this article discussion about CRC error is done, which include Cause of this error , how to tackle this error using some inbuilt utilities to repair corrupt Exchange BKF.

Cause of this Error:

CRC Error , which is also Known as cyclic Redundancy check , generally occurs when either Transaction log files are missing or header files are corrupt. As this error is due to corrupt Log files so it is bit difficult to trap and to handle.

But there are some inbuilt database utilities of MS Exchange Server which could  be used to repair and restore original Exchange database .

Inbuilt Utilities to fix CRC Error :

As missing Log files is the main reason behind this error so you can restore original Exchange database by restoring Active Log files. Inbuilt utilities such as Esseutil, Isinteg could be used to repair corrupt Exchange BKF file.

Using Eseutility for Exchange BKF file Repair:

Eseutility supports offline defragmentation, integrity check and hard repair of corrupt Exchange databases.Before running Esseutil command, ensure that selected Exchange databases is dismounted from Exchange Server.
To restore original Exchange database with inbuilt tool in follow thes steps:

1. In the command box, type “cmd” and press Enter to open DOS command prompt
2. Open Program Files\Excsrvr\bin directory at command prompt and type Esseutil
3. The command line will look like this

C:\ Program Files\Exchsrvr\bin> Esseutil

You can use any repair switch /p or /r with Eseutil to perform hard database recovery. For which command line will appear like this:

Esseutil/p EDB or log file name 
Esseutil/r EDB or Log file name

After recovering exchange Information store using Eseutility.exe utility, it is needed to perform complete database integrity check with Isinteg.exe utility of MS Exchange Server

Using Isinteg for Exchange BKF file Repair:

Isinteg utility fixes some unresolved corruption issues of Exchange Database files. This command will detect all the errors in the Exchange Database .User must use Isinteg command till no error is reported or shown on Exchange Server.

Isinteg.exe is located in same directory path as Eseutility.exe i.e., Program Files\Exchsrvr\Bin.

Command line to perform complete integrity check on all un-mounted EDB and Transaction Log files is:

Isinteg –s Servername [-fix]

Both these Esseutil and Isinteg utilities help network administrator to retrieve exchange BKF database and to repair it from corruption state.

NOTE: After trying all above manual solutions for Exchange BKF file recovery if still you are unable to access your Exchange database, then only option left with you is to use a professional Exchange BKF recovery tool, as these tools are capable of repairing severely corrupt/ damaged Exchange BKF files to provide access to your Exchange mailboxes, storage groups, public folders, and other BKF file items again.


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