Whether you own small or a big organization, you ought to make proper power arrangements to ensure the uninterrupted working of their computer systems. Still, a power failure may occur occasionally due to some unavoidable reasons. In case you are working on the Exchange database, it will create mounting problems during such a circumstance. This will eventually halt your online business communications in their entirety, keeping you isolated from your clients, employees, and other stakeholders. This blog provides several reasons behind the mounting error and discusses crucial Exchange recovery steps.
What causes the ‘Exchange database won’t mount ’ error after a power failure?
An abrupt power failure is likely to cause database mounting errors for several reasons. Here is a detailed description of the most common factors:
- Dirty Shutdown: A power outage can suddenly shut down the Exchange Server before all the pending transactions recorded in the transaction logs are committed to the Exchange database. This can cause the database to enter the Dirty Shutdown state, necessitating the need for a log replay or recovery, and enabling the admin to mount it successfully.
- Mismatch in transaction logs: A power failure can corrupt the log sequences. It can also lead to mismatched or missing log files and critical checkpoints.
- Exhausted disk space: A power failure can lead to failed backups, leading to a quick accumulation of transaction logs. This will eventually case the disk space to exhaust
- Corrupted database or file system: Frequent power outages can cause severe corruption in the storage subsystem or low-level logical file system.
- Loss of DAG quorum: In a clustered Exchange environment, a power failure can cause the Database Availability Group (DAG) to lose the quorum, which is the minimum number of witnesses or nodes needed to stay online. This will stop the cluster operations and prevent the mounting of the database.
- Exchange services go unresponsive: The Microsoft Exchange Information Store or its dependencies may fail to start automatically because of a sudden power failure.
How to restore Exchange mailboxes after a database mounting error
A power failure can lead to a database mounting error. For the smooth working of the organization, prompt resolution of such Exchange errors is crucial. Here are some suitable ways to resolve this error.
Exchange recovery using the soft repair method
Before trying this method, make sure to take a backup of the corrupt Exchange database. It will help to restore Exchange mailboxes if none of the methods works.
- To start recovery, run the Eseutil command below:
Eseutil /mh “Location of Database”. It will find the state of the Exchange database
Example:
Eseutil /mh “C: Program Files\ EDB DATA \ Exch001.edb”
- If you get a clean shutdown state, it indicates the consistent state of the database. However, it may still face issues during mounting. In case of a Dirty Shutdown state, you will need to repair the Exchange database. In both cases, you should proceed with soft recovery.
- Use the following Eseutil command to perform soft recovery
Eseutil /r <Log Prefix> / Location of Log files / d “Location of Database”
Example:
Eseutil /r E00 /l ““C: Program Files\ EDB DATA” /d “C: Program Files\ EDB DATA”
This command will replay the transaction logs into the Exchange database.
- Check the status of the database again by using Eseutil /mh
- The success of the soft recovery will lead to a clean shutdown state. If it still shows a dirty shutdown state, you may opt for other options.
Restore the Database from a backup
When the Eseutil method does not work, and you have a backup of the corrupted database, you can use it to restore the database. It will not fix the mount error, but will replace the damaged database with a healthy and consistent copy that you can mount without hassles.
You can do this with the help of the built-in Windows Server Backup facility, through the Recovery Wizard. So, make sure you have the Windows Server Backup feature installed on your local computer. The steps are as follows:
- Navigate to start menu and click Start > Windows Administrative Tools
- Click Windows Server Backup > Local Backup
- Under the Actions pane, click Recover to start the wizard
- In the Getting Started page, do the following:
- If the backup is on the local server, choose the option, This server (Server Name) > Click Next.
- If the backup is on another server or computer, select Another Server > Click Next
- In the resulting Specify location type page, choose Local drives or Remote Shared folder
- Select Next.
- If you select Local drives, choose the drive that contains the backup on the Select backup location page
- If you select Remote shared folder, provide the UNC path for the backup data on the Specify remote folder and click Next.
- Next, on the Select Backup Date page, choose the backup that you wish to recover along with the date and time, and click Next.
- In the resulting Select Recovery Type page, choose Applications > Next
- In the Specify Recovery Options page, specify the location where you want to recover the data and select Next
- You can choose from Recover to original location or Recover to another location
- Finally, you will see the Confirmation page to review all the recovery settings you just configured.
- After a careful review, click Recover to get the Recovery Progress page, which will let you check the progress of your recovery operation
- After the completion of the recovery operation, select Close
Recover Mailboxes from a Recovery Database (RDB)
Another widely used method to recover mailboxes from a corrupt Exchange database is to use a Recovery Database. It enables you to retrieve data from a database backup without affecting or overwriting the live database. Here is a brief description of the RDB method:
- Extract the backup files to a different location.
- Use Eseutil to ensure the Clean Shutdown state of the backup files
- Mount the RDB, overcoming the mount failure error
- Restore the selected mailboxes
This Microsoft page will give you the complete process to restore data through the Recovery Database
Exchange recovery using the hard repair method
If these methods do not work, you may opt for hard repair as the last option. Here is the command to perform this operation.
Eseutil /p <Location of database>
Example:
Eseutil /p “C: Program Files\ EDB DATA \ Exch001.edb
This method will also work in case of missing or corrupted log files. To be on the safe side, keep this method as the last resort, as it will purge all the corrupted data files from the database. This will lead to significant data loss. Instead, using an Exchange recovery tool will be a more feasible alternative in this regard.
Limitations of manual recovery methods
These methods can fix your database corruption directly or indirectly, allowing you to mount the database without errors. However, they come with several limitations:
- Consume considerable time
- Need in-depth technical knowledge
- Require the necessary permissions to perform the operations
- Can cause increased downtime if the process halts in between
- There is always the possibility of data loss, especially in the case of a hard repair
Using Exchange recovery tools
To avoid the hassles of manual recovery from a database mounting error caused by a power failure, admins try several automated Exchange recovery tools. These applications help to fix the database mount errors and restore Exchange mailboxes in a technologically better way. Stellar Repair for Exchange can be a feasible option to assist your cause in this context.
Conclusion
At times, a power failure can cause problems in mounting your Exchange database. You get the ‘Exchange database won’t mount ’ error as a result. Multiple reasons can lead to this situation, such as a Dirty Shutdown state, transaction log mismatch, insufficient disk space, corrupt file system, and so on.
To fix this error, you may try different methods. Prominent among these ways include Eseutil commands for soft repair, recovery database, restoring from a backup, or trying a hard repair. All these methods can resolve the issue, but may accompany several limitations, such as increased downtime, data loss, the need for high technical acumen, and more.
Perhaps using an automated Exchange recovery tool, such as Stellar Repair for Exchange, would be a better move to avoid these hassles. It can help to mount the database and restore Exchange mailboxes without errors.
