Apache NiFi Registry System Administrator's Guide
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Flow Persistence

If using the FileSystemFlowPersistenceProvider, the directory where flows are stored should be backed up periodically to an external location. In order to ensure a proper backup, NiFi Registry should be stopped to ensure no flows are being written to disk. If using H2 for metadata, H2 should be backed up at the same time to ensure consistency between the flows on disk and the contents in H2.

If using the GitFlowPersistenceProvider, the ability to automatically push to a remote may be configured. This provides an automatic backup of the data in the remote repo.