Overview
NOTE: This article only concerns using the default indexing engine (dtSearch).Vault index data is redundant data, it is not absolutely necessary to back it up as it can be rebuilt. However, especially in large vaults, loss of index data will result in a demanding indexing operation, during which full text searches from the data (metadata or file data) will not work until the indexing has finished.
Solution
Therefore, it is recommended to take backups of this data from time to time, especially in larger vaults, so in case the data is lost, a full index rebuild is not necessary.
To backup this index data, the safest way is to stop the M-Files indexing service and wait until all "mfindexer.exe" processes have disappeared from Task manager. When this has been done, the index data can be backed up: Copy the contents of the corresponding Indexes folder to the safe place. The path is usually like following:
C:\Program Files\M-Files\Server Vaults\[vault name]\Indexes
Then, start the indexing service. To restore this data, stop the indexing service, restore the data and start the indexing service - indexing will then continue from the first document NOT yet indexed. However, please note that you should match this index to your backups, so that it is always older than the backup of your file data and metadata.
