Schedules and retention - DeltaSnap Docs

Schedules are per APFS volume and run in the background helper. The main window does not need to remain open.

Choose which volumes DeltaSnap manages

Track Volume sits in the volume header, immediately left of the automatic-snapshot card. It is the master switch for that volume.

Turn it off and DeltaSnap leaves the volume alone: no automatic snapshots, no indexing, no background enumeration, no Finder badges, and nothing reported about it in helper health. Snapshots already on the volume stay listed and can still be deleted by hand, the same read-only treatment a Time Machine destination disk gets.

This is the setting to reach for when a drive is attached mostly as a backup destination, or is simply none of DeltaSnap's business. Turning tracking off also parks that volume's schedule, so switching it back on later does not silently start taking snapshots you did not ask for.

Two things worth knowing:

Untracked means untracked in both directions. DeltaSnap stops deleting on that volume too, so snapshots there stop expiring on their natural lifespans and hold their space until you remove them or switch tracking back on.
Turning a volume off never needs a licence. If a trial lapses, you can always tell DeltaSnap to stop touching a drive.

The dsnap equivalent is dsnap schedule set <volume> --tracked=off.

DeltaSnap rotates active automatic cadences, expires uncovered automatic and safety snapshots, and prunes unprotected history gradually under low space.

Cadences and default counts

Cadence	Boundary	Default kept	Natural lifespan when not actively rotated
Frequent	every 15 minutes	4	1 hour
Hourly	top of each hour	24	24 hours
Daily	local midnight	7	7 days
Weekly	Monday midnight	4	30 days
Monthly	first of month	off by default	365 days

New policies enable Frequent, Hourly, and Daily, covering about the last week with 35 snapshots. Weekly and Monthly start off; Weekly is prefilled with 4 when enabled, and Monthly can keep from 1 to 12. Missed boundaries while the Mac sleeps are skipped rather than replayed in a burst.

Open Configure… in the volume header to edit the policy for that volume.

DeltaSnap Snapshot Schedule sheet with frequent, hourly, daily, weekly, and monthly cadences enabled and their keep counts. — Each cadence has its own switch and keep count, and the sheet totals how many snapshots the policy will hold.

Three automatic deletion paths

Count rotation removes automatic snapshots beyond the keep count of an enabled cadence.
Lifespan expiry removes safety snapshots after their configurable TTL and automatic snapshots whose cadence is no longer actively rotating them.
Low-space pruning removes oldest eligible snapshots in small batches when free space falls below the per-volume threshold. It is the only automatic path that can remove manual snapshots.

There is no user-configurable “delete everything older than N days” rule.

The one-clock rule

An uncovered automatic snapshot's lifespan starts from the latest of its creation, this installation's first discovery of the volume, or the moment its cadence/schedule stopped rotating. Nothing expires by lifespan within 24 hours of first discovery. The TTL column shows the applicable estimate.

Low-space behavior

The default threshold is 30 GB with a 5 GB floor. DeltaSnap deletes gradually, waits for APFS accounting to settle, and aims above the threshold to avoid repeatedly hovering at the trigger. It keeps the newest snapshot of each cadence and never automatically deletes the last snapshot on a volume.

Lower half of the Snapshot Schedule sheet with the low-space pruning threshold set to 30 GB and the switch protecting Time Machine and other apps' snapshots. — The same sheet holds the per-volume pruning threshold and the switch that decides whether third-party snapshots are eligible for low-space pruning.

Low-space pruning defaults on for the internal startup Data volume and off for newly discovered external volumes.

DeltaSnap posts a general notification as free space approaches the threshold, and a critical one when it is below the threshold with nothing left it is allowed to prune. Both can reach you by email; see Notifications and email alerts.

DeltaSnap volume header showing a low free space warning that automatic pruning is active, above a snapshot table with expiry and private size columns. — When free space crosses the threshold, the volume header says so and the snapshot table's **Expiry** and **Private Size** columns show what is due to go and what deleting it returns.

What every pruner skips

protected snapshots;
mounted or actively leased snapshots;
com.apple.os… snapshots;
snapshots on Backup-role volumes; and
third-party snapshots while Protect Time Machine and other apps' snapshots is enabled. This now starts on, because DeltaSnap can present another tool's snapshot as browsable, restorable history and deleting one to reclaim space would destroy that tool's restore point. Third-party points are excluded from count, lifespan, and safety-TTL pruning either way, and become relevant only to low-space pruning.

The global Settings → General → Automatic Deletion switch is an additional commit-point gate. Turning it off keeps manual deletion available.

CLI policy controls:

dsnap schedule show data
dsnap schedule set data --freq=4 --hourly=24 --daily=7 --weekly=4 --monthly=1
dsnap schedule enable data
dsnap schedule disable data

The CLI edits counts and pruning values; enable or disable individual cadences in the app.