Avamar: Exchange database restore failing with avtar error stating database not found in backup

Scenario:

• The requirement is to restore an Exchange Database, which we call "Database4" for this example.
• The database restore process fails with a message in the log stating that the Database4 path is not found in the backup piece, however, the database is available for restore in both the Avamar user interface (GUI and AUI).
•  This is the type of error message seen in the restore log:

avtar Error <5195>: Path "EX-Node3_00000000\H:\mountpoints\Database4\Database4.edb" not found in backup. (Element 'Database4.edb' at position 3 in search path 'EX-Node3_00000000\H:\mountpoints\Database4\Database4.edb' not found) 

• Restoring another Database (for example Database2) from the same backup piece and the same Exchange Server works as expected. 

The Exchange environment presents a non-standard database configuration that Microsoft supports but it is known to cause this issue to the Avamar product.

In this scenario, the affected database (Database4) presents an inconsistent case capitalization in the database file path.
There is a mismatch between the OS "database storage path" and the Exchange Application "database location path"
 
Example of an affected database (Database4):
Paths mismatch:

• The OS path for the DBs was created with the "Mount Point" folder in upper cases (letters M and P)

H:\MountPoints\Database4\Database4.edb

• The Database4 path in the Exchange application was configured with all letters in lowercase:

H:\mountpoints\Database4\Database4.edb

Example of a non-affected database (Database2):
The OS database's path and its corresponding path within the Exchange configuration have the same case capitalization:

• Database storage path

H:\MountPoints\Database2\Database2.edb

• Database location path

H:\MountPoints\Database2\Database2.edb

 
To verify those paths:

• Use Windows Explorer to check the OS path
• Use the Exchange admin center (EAC) to check the database configuration
  • => servers/databases/<edit properties of the affected DB>
    • Alternatively, use the Exchange Powershell command:

Get-MailboxDatabase -Identity <affected DB name> | Select-Object edbfilepath, logfolderpath | fl

The case mismatch condition causes the Avamar process (avtar) to log the incorrect database information in the backup metadata during the backup process.

At restore time, the avtar process does not identify the correct database's path. Therefore, it fails to restore the database by printing the message "database not found in backup"

To resolve this database's case mismatch situation, the Avamar product counts with a flag called "--use-case-sensitive-paths" which takes care of these types of scenarios.

• The flag must be added in the "avexvss.cmd" file under the Avamar client var folder (default path "C:\Program Files\avs\var\") in all Exchange DAG nodes that participate in the backup process.
• Also, for DAG federated backups, the flag must be added in the "avexvss.cmd" file under the Cluster client's var directory
  • This is the UNC path shared between the DAG nodes and is needed to coordinate backups and to store DAG client configuration and log files
    UNC Path Example "\\share-server\share-folder\DAGname\var\")
• The flag value must be set as "false" (its default value is "true"):
  • --use-case-sensitive-paths=false

• If the flag is only added to the proxy node (in IP-Less DAG configuration) or cluster client (in Federated configuration), the backup succeeds but the restore might fail this same issue.
• Therefore it is important to add the mentioned flag in every Exchange node (of the DAG cluster) participating in the backup process.

 
Setting this flag as "false" ensures that all future backups are not affected, and that restoration is successful for those new backups.

Older backups are not fixed using this flag and require a specialized procedure to be restored.

This special procedure is described in Avamar: How to restore an Exchange database from a backup affected by the Database path case-mismatch issue.

• If the mentioned flag is not used in an Exchange environment that presents the case capitalization mismatch the backup may fail with this error:

avtar Error <7042>: Failed to create snapview, as one of the elements required for path "XXXXXXXXX.edb" not found in backup account '/XXXXXX' lablenum 3 (only found 'XXXX\E:' of path 'XXXX.edb').

• This is described in the Avamar for Exchange VSS User Guide under the chapter "Troubleshooting" section "Backup fails due to case sensitivity"
• It is also documented in Avamar: Exchange VSS backup failing with avtar Error "Failed to create snapview, as one of the elements required for path "XXXXX.edb" not found"