The first version of HAMMER took automatic snapshots, set within the config for each filesystem. HAMMER2 now also takes automatic snapshots, via periodic(8) like most every repeating task on your DragonFly system.
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Actually, automatic HAMMER snapshots are also accomplished via periodic, it’s just “hidden” under all-in-one “hammer cleanup” call in /etc/periodic/daily/160.clean-hammer. But yes, these snapshots are managed by a config file placed directly on particular filesystem.