Can an incremental forever backup strategy be used to protect a mounted NAS storage on a Linux client?
Incremental backups use a journal to track changes in a file system. The journaling process on LInux uses the inotify kernel subsystem to track changes. Inotify will only detect changes on file systems that are directly connected to the server on which the Linux agent is installed. Remote file systems that are mounted on a Linux server will not send notifications to the local kernel so the change journal will not contain changes to these remote file systems. To protect these file systems via incremental forever you must either install an agent on the server that hosts these file systems, or you can configure NAS storage on the Unitrends system and back up the files using backups on the appliance itself. NAS backups do not use the Journal but instead use the directory traversal/file modification time scanning technique in order to determine which files should be included in a backup.
See AlsoLinux Change Journal