Log files are the crucial components of Exchange Server. And if log files get corrupted, it can become the reason of mount failure and other problems for Exchange Server database. Microsoft Jet engine can fix the log files that have been corrupted due to torn writes. Since the log file data cannot be safely rebuilt, it is rejected and is not applied on the database. Such situations usually occur because of hardware failure, which might leave your database in inconsistent state. Failure of data backup makes the problem even more disastrous and requires you to apply exchange server recovery solutions to repair the database.
To be more specific, here is a scenario that briefly explains the consequences of log file corruption in Microsoft Exchange Server. Let's say, you run an Exchange Server database that suddenly fails to mount. On viewing the application event log, you receive the following event:
Event ID: 477
Description: <process name>(<process id> <storage group name>The log range read from the file "<file name>" at offset <value> for <number> bytes failed verification due to a range checksum mismatch. The read operation will fail with error <error code>. If this condition persists then please restore the logfile from a previous backup.
Similar event can also log when you fail in your attempts to perform an online backup or online restore of the same database.
Exchange Sever is unable to repair the damage to the log file. The exact explanation of event 477 depends on the error code you receive in 'Description' section of the above event:
-501 or JET_errLogFileCorrupt. The log file is corrupt. The database is inconsistent and you cannot mount it.
-573 or JET_errLogCorruptDuringHardRestore. There is corruption in backup store that has been detected during hard restore and thus, you cannot perform an online restore.
-612 or JET_errLogReadVerifyFailure. Log file contains checksum errors that won't allow you to perform an online backup of Exchange Server database.
Methods to Solve
Restore the affected log file from a good backup
Remove the affected log files and all other log files created after it and restore the database from an online backup
Restore from an earlier backup in case of error -573
Backup your Information Store and run hard repair using Eseutil /p utility. Use ExMerge and merge the mailboxes to a new store.
If none of the above solutions works, use an exchange recovery utility. Exchange Server Recovery utilities are effective tools that can safely restore the database contents to a safe location.
Stellar Phoenix Mailbox Exchange Recovery is a high-end tool used to repair corrupted Exchange Server database and allows selective mailbox recovery at a secure location. Supporting MS Exchange Server 2007, 2003, 2000, and 5.5, this Exchange Recovery tool creates an individual PST file for each mailbox.
Some Tips to Solve Exchange Server Event 477