Compactor Mode | XMigrate Docs

Overview

The compactor merges older incremental backups into new full snapshots, reducing storage usage and improving restore performance. It reads compaction policies from the cloud configuration file.

Manual Usage


# Dry-run (default) — prints planned actions without modifying anything
xreplicator compact --repo /var/lib/backup/repo
 
# Actually perform compaction
xreplicator compact --repo /var/lib/backup/repo --dry-run=false
 
# Use a custom cloud config
xreplicator compact --repo /var/lib/backup/repo --cloud-config /etc/xreplicator/cloud-config.yaml

Flag	Required	Default	Description
`--repo`	Yes	—	Repository path
`--cloud-config`	No	`<repo>/cloud-config.yaml`	Cloud config path
`--dry-run`	No	`true`	Print actions without modifying snapshots

Compaction Policies

Policies are defined in cloud-config.yaml under the compaction.policies section.

Policy Parameters

Parameter	Type	Required	Description
`name`	string	Yes	Unique policy name
`enabled`	boolean	—	Enable/disable this policy (default: `true`)
`compact_to_full`	boolean	—	Create a new full snapshot from compacted incrementals (default: `true`)
`rpo`	duration	Yes	Compact snapshots older than this value (e.g., `"24h"`)
`keep_snapshots`	integer	No	Minimum recent snapshots to keep, even if older than RPO
`hostnames`	string[]	No	Exact hostnames to match
`hostname_globs`	string[]	No	Glob patterns for hostnames (e.g., `["prod-*"]`)
`device_paths`	string[]	No	Exact device paths to match
`device_path_globs`	string[]	No	Glob patterns for device paths

Use either hostnames or hostname_globs — not both. Same applies to device_paths vs device_path_globs.

How Compaction Works

Policy Evaluation — Reads all enabled policies from the cloud config
Snapshot Selection — Finds snapshots matching hostname/device criteria
Age Filtering — Filters snapshots older than the RPO, respecting keep_snapshots
Compaction — Merges selected incrementals into a new full snapshot
Cleanup — Deletes old incrementals that were compacted
Chain Update — Updates parent links in remaining snapshots

Configuration Examples

Daily Compaction (All Devices)


compaction:
  policies:
    - name: "daily-compaction"
      enabled: true
      compact_to_full: true
      rpo: "24h"
      keep_snapshots: 10
      hostname_globs: ["*"]
      device_path_globs: ["*"]

Weekly Compaction (Production Servers)


compaction:
  policies:
    - name: "weekly-production"
      enabled: true
      compact_to_full: true
      rpo: "168h"   # 1 week
      keep_snapshots: 5
      hostnames: ["prod-server-01", "prod-server-02"]
      device_paths: ["/dev/sda"]

Multiple Policies


compaction:
  policies:
    - name: "daily-all"
      enabled: true
      compact_to_full: true
      rpo: "24h"
      hostname_globs: ["*"]
      device_path_globs: ["*"]
 
    - name: "weekly-production"
      enabled: true
      compact_to_full: true
      rpo: "168h"
      keep_snapshots: 10
      hostname_globs: ["prod-*"]
 
    - name: "monthly-archive"
      enabled: true
      compact_to_full: true
      rpo: "720h"   # 30 days
      keep_snapshots: 3
      hostname_globs: ["archive-*"]

Scheduling with systemd Timer

If you want scheduled compaction, create your own systemd timer that runs the xreplicator compact command from the backup-server package.

You can also schedule compaction from the Web UI: go to Settings and configure the compaction schedule there. You can also create and edit compaction policies directly from the UI.