This page help customer setup a ceph file system snapshot schedule. And, Setup Samba server shadow copy backed by Cephfs

A Ceph File System (CephFS) can schedule snapshots of a file system directory. The scheduling of snapshots is managed by the Ceph Manager, and relies on Python Timers. The snapshot schedule data is stored as an object in the CephFS metadata pool, and at runtime, all the schedule data lives in a serialized SQLite database.

Snapshot schedules are identified by the file system path, the repeat interval, and the start time. The repeat interval defines the time between two subsequent snapshots. The interval format is a number plus a time designator: h(our), d(ay), or w(eek). For example, having an interval of 4h, means one snapshot every four hours. The start time is a string value in the ISO format, %Y-%m-%dT%H:%M:%S, and if not specified, the start time uses a default value of last midnight. For example, you schedule a snapshot at 14:45, using the default start time value, with a repeat interval of 1h, the first snapshot will be taken at 15:00.

Retention policies are identified by the file system path, and the retention policy specifications. Defining a retention policy consist of either a number plus a time designator or a concatenated pair in the format of COUNTTIME_PERIOD. The policy ensures that a number of snapshots are kept, and the snapshots are at least for a specified time period apart. The time period designators are: h(our), d(ay),w(eek), m(onth), y(ear), and n. The n time period designator is a special modifier, which means to keep the last number of snapshots regardless of timing. For example, 4d means keeping four snapshots that are at least one day, or longer apart from each other.

Prerequisites:

• Pacific ceph cluster or later
• Active and running ceph file system
• CephFS snapshot schedule module enabled 

Step1: Enable Ceph file system snapshot schedule

# enable snap schedule
ceph mgr module enable snap_schedule

# check if snap schedule is active
ceph mgr module ls |grep snap_schedule
snap_schedule         on

ceph fs snap-schedule add FILE_SYSTEM_VOLUME_PATH REPEAT_INTERVAL [START_TIME] --fs CEPH_FILE_SYSTEM_NAME

# add snap schedule to / or other path like /template/iso
# for example add /tmplate/iso witch will run snapshot every hour, starting from the default value last midnight.
ceph fs snap-schedule add /template/iso 1h --fs cephfs

ceph fs snap-schedule retention add FILE_SYSTEM_VOLUME_PATH [COUNT_TIME_PERIOD_PAIR] TIME_PERIOD COUNT

# add retention to keep the max number of snapshots 
# make snapshot for /template/iso to keep max 24 snapshots at least one hour apart.
ceph fs snap-schedule retention add /template/iso h 24 --fs cephfs

# make snapshot for /template/iso to keep 12 hourly, and 3 weekly snaps
ceph fs snap-schedule retention add /template/iso 12h3w --fs cephfs

# List snapshot schedule
ceph fs snap-schedule list FILE_SYSTEM_VOLUME_PATH [--format=plain|json] [--recursive=true]

# active the target path
ceph fs snap-schedule activate /template/iso --fs cephfs

# active all schedule behide the root directory
ceph fs snap-schedule activate / --fs cephfs

# Get snapshot schedule information
 ceph fs snap-schedule status /template/iso
{"fs": "ec42fs", "subvol": null, "path": "/template/iso", "rel_path": "/template/iso", "schedule": "1h", "retention": {"h": 24}, "start": "2024-08-16T00:00:00", "created": "2024-08-16T07:28:54", "first": "2024-08-16T08:00:00", "last": "2024-08-16T08:00:00", "last_pruned": null, "created_count": 1, "pruned_count": 0, "active": true}

        vfs objects = shadow_copy2
        shadow:format = _scheduled-%Y-%m-%d-%H_%M_%S_UTC_1099513208924
        shadow:snapdirseverywhere = yes
        shadow:snapdir = .snap

systemctl restart smbd