Exchange Mailbox Database Offline due to disk errors - How to repair?

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Disk errors can be the source of sundry problems for the Exchange server, the most common one being that the database fails to mount.

Subsequent issues from the user’s perspective include inaccessibility of mailbox data and possible threat of data loss. Stellar Phoenix Mailbox Exchange Recovery comes in handy to extract vital information from the dismounted database in such a scenario.

Microsoft Exchange despite being one of the most versatile emailing servers and used by a majority of organizations across the world, isn’t immune from troubles. Unexpected issues can often arise within Exchange causing it to deviate from its usual behavior and ending up with problems like database mounting failures. And when the database fails to mount, end users are the worst impacted since they face immediate mailbox inaccessibility and a halt in their work related activities.

A prominent trigger of Exchange database’s mounting failure is disk input / output (I/O) errors.

Exchange Disk Input / Output (I/O) Errors

The Exchange Management Pack for Operations Manager monitors the Windows Application log on computers that are running Exchange Server. It generates alerts when the event or events specified in a specific Details table are logged. Typically, when any ‘critical error’ of the disk I/O category arises, it is an indication that Extensible Storage Engine (ESE) was called by the Information Store (IS) service and it received an error from the operating system when the ESE tried to read or write to a file (database file, transaction log file, or checkpoint file). Such an event usually causes the affected databases to experience the “Exchange Mailbox Database Offline” problem with users being unable to send or receive e-mail.

A typical example of this kind of issue was observed when one of our clients recently contacted us with an error situation where their attempts to mount the Exchange database failed with the following log message:

Database copy on this server appears to have a serious I/O error. To help identify the specific failure, consult the Event log on the server for other storage. Service recovery was attempted by failover to another copy. Failover was unsuccessful in restoring the service. Error: There is only one copy of this mailbox database. Automatic recovery is not available.

Such a cryptic mounting error is enough to throw even the most experienced of Exchange Admins off track. Read the subsequent sections to find out what are the possible solutions you can try out when faced with a similar situation. Towards the end, we’ve also introduced a one-stop remedy for this and other Exchange errors which will help you ensure that your organization’s Exchange server never has to go offline.

How to solve Exchange Disk I/O Errors

When faced with disk I/O errors that cause the “Exchange Mailbox Database Offline” problem, here’s everything you should try out:

  1. Check the Application event log for errors and critical items and also check the System event logs to call out any disk/system related issues.
  2. Run CHKDSK to detect and fix minor disk issues.
  3. Move the checkpoint and logs to a temporary location and mount database to see whether it works.
  4. Restoring from backup may solve the immediate issue. Move the VM and log files to another system and then restore the DB from backup. However if there are disk related issues left unresolved the problem will most likely return.
  5. Check what state the database is in. If it is shown as in “Dirty Shutdown” state, run a hard recovery. Here are the steps:
    1. Run eseutil /mh *.edb command to check the current database state.
    2. If shown as “Dirty Shutdown”, run eseutil /p *.edb command. However, running a hard recovery on Exchange database might result in some data loss. Also, before executing this step, ensure that the drive that contains the database and log files has enough free space available to run hard recovery.
    3. Run eseutil /mh *.edb again to confirm that now the database is in “Clean Shutdown” state.
    4. Now move alllog files away from the default Exchange log folder (or wherever you store them) to a log corrupted storage.
    5. Now try to mount database

If even after trying out the above mentioned techniques you’re stuck with the same error, it means that your Exchange database (EDB) files have been corrupted. As such, the only way to get rid of the issue is to use third-party software Stellar Phoenix Mailbox Exchange Recovery which will help you recover dismounted EDB files and thus assist in mounting the database.

The best solution

A majority of MVPs across the world recommend Stellar Phoenix Mailbox Exchange Recovery as the product of choice when it comes to restoring emails from dismounted and offline EDB files. The software is backed by technically advanced algorithms that empower it to carry out deep scans of damaged, corrupted, and dismounted EDB files and spot issues. Thereafter, a non-destructive repair and recovery mechanism is carried out to fix found issues and facilitate easy extraction of mailbox items (emails, attachments, contacts, calendars). The tool offers users a chance to save the extracted items into Outlook PST files so that users can access their mailbox data easily.

In addition to the above mentioned capabilities, Stellar EDB Recovery Software is packed with a fully interactive GUI and a lot of other helpful features which make it the most favorable choice for situations precisely like the one discussed in this post.

Wrapping it up

When faced with challenging scenarios like Exchange disk errors, usually a lot of manual resolutions are readily available. But most of them need a lot of prior technical knowhow and caution to be performed. Additionally, they are subject to a high risk of data loss. Thus, sticking to the most clear-cut and concise approaches is advisable. Stellar Phoenix Mailbox Exchange Recovery makes for the best and safest approach in such cases.


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