If you encounter the 'unable to mount the database' issue in any version of Exchange Server, including 2010, 2013, and 2016, it's crucial to understand the significance of transaction logs.
Transaction logs are vital for the proper functioning of an Exchange Server, serving as its lifeblood. They capture every transaction made on the server, which is then recorded in these log files before being committed to the database. These transactions reside in system memory and the transaction logs until they are stored in the database.
In the event of a crash during this process, the content stored in memory is lost during the reboot since it wasn't fully saved to the Exchange database files. This highlights the critical role of transaction logs as a robust recovery mechanism, ensuring the safe restoration of data to an Exchange database in a consistent state.
You encounter the following error message when attempting to mount the database back on the Exchange Server.
Exchange is unable to mount the database that you specified. Specified database: d1cdba46-6f79-46f2- ba14-3ae2fa8aad43; Error code: MapiExceptionCallFailed: Unable to mount database. (hr=0x80004005,ec=-2147467259)
Importance of Log Files
In Exchange Server 2010, transaction logs and checkpoint files play a crucial role in preventing data loss. The transaction log records all the changes committed in the in-memory database, while checkpoint files keep track of the logged transactions that are committed to the on-disk database files.
In Exchange Server 2010, each database has a unique set of transaction logs. These logs serve as a record of changes made before they are officially committed to the database file.
If the database disk becomes damaged while the transaction logs remain intact, the restoration process enables you to recover the data from the media back to the database. During this process, the Exchange Store accesses the transaction log files and replays the previously executed database transactions. Subsequently, it replays the remaining on-disk transaction log files. However, there is a risk of transaction failures if a system failure occurs between two recorded transactions in the logs, potentially causing issues with the effectiveness of the transaction log restore in such cases.
- Deletion of transaction logs, which were pending to be committed in database.
- Corrupt Database.
- Dirty Shutdown State.
Microsoft offers the Eseutil utility, which serves as a tool to determine if the database is in a clean shutdown state. If it's not in a clean shutdown state, this built-in utility can assist in addressing the issues and restoring the database to a consistent state. In cases where the data is in an inconsistent state, the following resolution steps can guide you in successfully restoring the information from the backup.
The removal of a log file is a common factor that can lead to database mounting failures. To address such issues, it's crucial to begin by conducting a consistency check.
The Eseutil tool can be highly valuable for conducting a soft recovery, particularly when you need to remount a database after an abrupt stop. To perform this process, follow the steps below:
- Run eseutil /mh command
- If the output displays the database in a dirty shutdown state as shown below, then the database is missing a transaction log.
- To bring back the database into consistency, it is essential to replay log files into the database. Run the command in ESEUTIL
eseutil /r /l /d - Then provide the location on which the logs are stored
For example: G:\E_\Program Files\Microsoft\Exchange Server\V14\Mailbox\DAGDB1 - When the repairing process gets complete, then again perform this action: Run eseutil /mh command. Doing so will let you verify that the database is in a clean shut down state or not.
- Now, you can mount the database back to exchange using the command -
Mount-MailboxDatabase -Identity '-DAGDB1.edb' However, if you are still unable to mount the database, then verify the consistency of transaction logs.
Verify and Repair Database Logs Using Hard Repair
Eseutil tool is even helpful in performing hard repair recovery to test the database for any damaged pages. If there are any, then the tool will delete them. Run the hard repair - Eseutil /p '\DAGDB1.edb'
If you're still unable to mount the database, consider utilizing a dependable third-party Exchange EDB Recovery tool that can efficiently restore data under any condition of damage, even when the Eseutil tool falls short. This advanced recovery tool is designed to repair corrupt Exchange database files without the need for log files or Exchange services. Additionally, the advanced recovery tool to repair corrupt Exchange database files, without requiring log files or Exchange services. EDB to PST converter tool offers the capability to directly restore EDB files to a live Exchange Server and Office 365 mailbox.
