Pruning Snapshots

plakar prune removes snapshots from a Kloset store. Snapshots can be selected for removal by age, tag, or retention policy.

Every backup you run creates a new snapshot in your Kloset store. If left unchecked, snapshots can accumulate indefinitely.

Pruning lets you define how much history you actually need — such as keeping hourly snapshots for the past week, daily ones for the past month, monthly ones for the past year — and discard everything else. This keeps your store from growing without bound while preserving important recovery points.

By default, plakar prune runs in dry-run mode and makes no changes. You’ll need to pass -apply to execute the operation.

In this guide, we will use a Kloset store located at $HOME/backups, but your store can be located anywhere else.

Before removing anything, check which snapshots would be affected:

$ plakar at $HOME/backups prune -days 30

No snapshots are deleted without -apply. The output shows what would be removed.

To delete snapshots older than 30 days:

$ plakar at $HOME/backups prune -days 30 -apply

You can use other flags like -weeks, -months, or -years to specify age.

To delete snapshots older than 30 days that carry a specific tag:

$ plakar at $HOME/backups prune -days 30 -tag daily-backup -apply

Only snapshots matching the tag are considered. Others are left untouched.

A retention policy keeps a defined number of snapshots across different time windows and deletes everything else. This is the most common way to keep a store bounded over time.

$ plakar at $HOME/backups prune \
  -days 1 -per-day 7 \
  -weeks 4 -per-week 1 \
  -months 12 -per-month 1 \
  -years 5 -per-year 1 \
  -apply

This can be broken down as:

• -days 1 -per-day 7 — For the past day, keep up to 7 snapshots. This preserves frequent checkpoints in the most recent period.
• -weeks 4 -per-week 1 — For the past 4 weeks, keep 1 snapshot per week. Older intra-day snapshots are pruned down to a single representative per week.
• -months 12 -per-month 1 — For the past 12 months, keep 1 snapshot per month.
• -years 5 -per-year 1 — For the past 5 years, keep 1 snapshot per year.

Everything outside those windows is deleted.

By default, retention rules apply across the entire result set as a whole. The -group-by flag partitions snapshots by a metadata key first, then applies retention rules independently within each group.

This matters when your store contains snapshots from multiple sources. Without grouping, -per-day 1 keeps a single snapshot for the day regardless of which machine or job it came from. With -group-by name, it keeps the newest snapshot per name for the day.

The general form is:

$ plakar at $HOME/backups prune -days 30 -per-day 1 -group-by <key> -apply

Supported keys:

Keys like tag, origin, type, root, and data-class are multi-valued: a snapshot can belong to more than one group. In that case, the snapshot participates in retention evaluation for each group it belongs to, and a keep decision in any group takes precedence over delete.

A store holds snapshots from several different backup jobs, each identified by a distinct name. To keep the most recent snapshot per name for the last 30 days:

$ plakar at $HOME/backups prune -days 30 -per-day 1 -group-by name -apply

Without -group-by name, only a single snapshot across all jobs would be kept per day.

To apply the same per-week retention independently to each environment:

$ plakar at $HOME/backups prune -weeks 4 -per-week 1 -group-by environment -apply

-group-by composes naturally with -policy:

$ plakar at $HOME/backups prune -policy weekly -group-by name -apply

Rather than specifying retention parameters on the command line each time, a named policy can be defined once and reused.

You can create a policy and configure its retention parameters:

$ plakar policy add weekly
$ plakar policy set weekly since='3 months'
$ plakar policy set weekly per-week=1

Then apply the policy:

$ plakar at $HOME/backups prune -policy weekly -apply

$ plakar policy show              # list all policies (YAML by default)
$ plakar policy show -json        # output as JSON
$ plakar policy show weekly       # inspect a specific policy
$ plakar policy set weekly per-week=2   # update a parameter
$ plakar policy unset weekly per-week   # remove a parameter
$ plakar policy rm weekly         # delete a policy

Pruning removes snapshots, but does not immediately free storage. Because Plakar deduplicates data across snapshots, the underlying chunks and packfiles remain until plakar maintenance runs (also consider the maintenance grace period).

After pruning, run plakar maintenance to reclaim the freed space:

$ plakar maintenance

• plakar policy
• How maintenance works