Exchange Database Mounting – Top 10 Issues and Solutions

An Exchange mailbox database may fail to mount for various reasons. Following are some major reasons that lead to database dismount and prevent the Exchange database from mounting are as follows:

1. Inconsistent/Missing log files (Dirty Shutdown)
2. Low or no disk space
3. Database corruption due to a hardware fault or loss of power
4. Licensing
5. Database won’t mount error : (hr=0x80004005, ec=-501)
6. Database won’t mount error: (JET_errFileAccessDenied, Cannot access file, the file is locked or in use)
7. Time mismatch in the DB compared to the directory. (Unable to mount database.(hr=0x80004005, ec=-344))
8. Permission Problem.
9. Anti-Virus Problem.
10. The Exchange database won’t mount (Cannot see Active Directory)

Although the issue can be resolved by using various Exchange PowerShell cmdlets, it may sometimes lead to data loss.

Thus, to avoid any data loss or further problems and restore the mailboxes on the server, you can use Exchange Recovery software, such as Stellar Repair for Exchange. It will help you quickly restore the mailboxes on the Live Exchange server and resume mailbox connectivity that was lost due to the dismounted database.  

Below we have discussed the top 10 most common issues that lead to database dismount or mounting problems in detail, along with their solutions.

Inconsistent/Missing Log Files

The issue of inconsistent/missing log files may arise due to human error or a problem with backup software. I have seen administrators who, while trying to free up space, have deleted the log files from the Exchange directory. And when they reboot the Exchange, the databases don’t mount.

To fix this problem, you need to copy all the log files to another directory and then turn on circular logging to flush the log files. The database should mount again after that. After that, turn off circular logging and take a full backup of your Exchange database.

Low or No Disk Space

Exchange, if not provided with adequate storage space or not properly backed up with application-aware software, will consume almost all the space on a drive. This is because the logs will purge only when a successful backup is done.

To fix the problem, you can try any of the given three options:

• Take a backup of the mailbox database
• Manually purge the logs
• Increase the storage, if the machine is a virtual one
• Enable Circular Logging (works but not recommended)
• Create VSS Backups (auto-purges transaction logs, highly recommended)

Exchange Database Corruption due to Hardware Failure

Exchange databases may get corrupted when hardware such as hard drives, raid controllers, motherboards, or other components fail. This can result in the Exchange database, not mounting issues.

Depending on the hardware damage, you can’t do much, apart from rebuilding the Exchange server. However, the database is not so easily portable. To recover this database, you would have to look at a backup or use Exchange Recovery by Stellar Data Recovery to recover all the data.

Licensing

If you are running the Exchange Server Standard version, you have a limit of 5 databases. If in case, you are working with more than 5 databases, Exchange will only mount those databases and leave the others unmounted.

Since the databases are not mounted, you cannot move them to another and remove the unwanted databases. Therefore, there are only two solutions:

• Upgrade your license from Exchange Server Standard to Enterprise
• Use Stellar Repair for Exchange to export from the offline database to an online database

Database Mount Error: hr=0x80004005, ec=-501

If you have experienced a power outage or the VM/Physical server has been rebooted, you might encounter the following error messages:

Unable to mount database. (hr=0x80004005, ec=-501)

Database Mount Error: (JET_errFileAccessDenied, Cannot access file, the file is locked or in use)

If you experience these errors, there is a possibility that an application is holding onto the file. If you do not have any anti-virus exclusions in place, it is possible that the anti-virus is either removing log files or locking the .edb file to scan it, thus causing the error.

The solution would be to either disable the antivirus software or exclude the Exchange Folder. After this, you would be able to mount your database. However, there is a risk of corruption. To try fixing this database mount error, run the eseutil /p command to perform a soft recovery.

Time Mismatch Error Mounting Exchange Databases

This error means there is a time mismatch in the DB compared to the directory. The explanation of the ESE error code reads as follows: “JET_errDbTimeCorrupted -344 The Dbtime on the current page is greater than the global database dbtime. This error is returned by the directory manager.”

To fix this kind of error that is preventing Exchange databases from mounting, you should run the following eseutil /d for defragmentation.

After it has completed its defragmentation, it is advisable to move all the existing mailboxes to a new Exchange Database.

Permission Problem causing Exchange databases not to mount.

Another common Exchange database mounting issue is that the database won’t mount if the SeSecurityPrivilege right has been modified. If in fact, this is the case then you  might receive one of the following messages in the Application event log:

• Event 2102 : Process MAD.EXE (PID=1088). All Domain Controller Servers in use are not responding:
• Event 9004: The Metabase Update service failed to start, error ‘80040a01.’
• Event 1005: Unexpected error. An unknown error has occurred. ID no: 80040a01 Microsoft Exchange System Attendant occurred.
• Event 1029: Failed to replicate the security descriptor to the Metabase. Users may not be able to read or write data to the Metabase. Error code is 8000500d.
• Event 9074: The Directory Service Referral interface failed to service a client request. RFRI is returning the error code:[0x3f0].
• Event 1121: Error 0x80004005 connecting to the Microsoft Active Directory.
• Event 125: A fatal error occurred reading a value from the directory.
• To fix this kind of error that is stopping the .EDB from mounting, perform a domain prep again to put the rights back.

Anti-Virus Problems

In Exchange, if you have any kind of Anti-Virus installed, you need to ensure that all the exclusions are set. The reason being is that the Anti-Virus can delete log files or lock files while it scans, you might encounter the error JET_errFileAccessDenied when the database tries to mount. With the correct exclusions in place, it ensures that Exchange runs as it should without unnecessary pressure caused by the Anti-Virus Software.

Exchange database won’t mount (Cannot see Active Directory)

Here is another error you might come across when trying to mount an Exchange database:

Couldn’t mount the Exchange database that you specified. Specified database: Mailbox Database; Error code: An Active Manager operation failed. Error The database action failed. Error: Operation failed with message: MapiExceptionNotFound: Unable to mount database. (hr=0x8004010f, ec=-2147221233)

Here is another error you might come across when trying to mount an Exchange database.

Couldn’t mount the database that you specified. Specified database: Mailbox Database; Error code: An Active Manager operation failed. Error The database action failed. Error: Operation failed with message: MapiExceptionNotFound: Unable to mount database. (hr=0x8004010f, ec=-2147221233)

The first step is to try and mount it from the Exchange Management Shell. If that does not work, check that the Exchange can contact a DC which is a Global Catalog. You can use the Set-ADServerSettings command to force the exchange to use a specific domain controller.

After you have done that then the databases should mount successfully.

Conclusion

There are many reasons why an Exchange Database won’t mount. If you do not have a backup of your data, your only solution is to use EseUtil to do a soft recovery or a hard recovery, which would result in a loss of data. The last solution would be to restore from backup, but it would be a lengthy process and also result in data loss. On the other hand, you can use Stellar Repair for Exchange which can open the .EDB file and extract the data, and help you restore the Exchange server with minimal downtime.

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About The Author

Edward van Biljon (MVP)

Experienced Messaging Specialist with a demonstrated history of working in the information technology and services industry. Skilled in WSUS, Domain Name System (DNS), Data Center, Printer Support, and System Center Configuration Manager (SCCM). Strong information technology professional with a International Diploma in Programming focused in Computer Programming from CTI.