While running, Memgraph generates a couple of different files in its data directory. The directory includes multiple different subdirectories, one of them being the storage directory which contains the durability files. In that directory Memgraph periodically generates snapshots and WAL files that contain Memgraph's data in a recoverable format.
Making a backup of a Memgraph instance would consist of simply copying the data directory. This is not possible to do without additional help because the durability files can be deleted when an event is triggered (the number of snapshots exceeded the maximum allowed number).
To disable this behavior, you can use the following query:
LOCK DATA DIRECTORY;
Now, the deletion of every file contained in the data directory is delayed until you unlock it again. You can safely copy the data directory or a single snapshot to another location without worrying that it will be deleted during that process.
To allow the deletion of the files again run the following query:
UNLOCK DATA DIRECTORY;
Memgraph will delete the files which should have been deleted before and allow any future deletion of the files contained in the data directory.