Retention Schedules
Retention schedules determine how long backup versions are kept before being eligible for deletion. The One Backups uses the Grandfather-Father-Son (GFS) model — a tiered approach that keeps more frequent versions for recent data and progressively fewer versions as data ages.
Grandfather-Father-Son (GFS) Model
GFS divides retention into four tiers:
| Tier | Label | What It Keeps |
|---|---|---|
| Son | Daily | One version per day for the past N days |
| Father | Weekly | One version per week for the past N weeks |
| Grandfather | Monthly | One version per month for the past N months |
| Great-Grandfather | Annual | One version per year for the past N years |
At each tier boundary, older daily backups are pruned and only the designated weekly, monthly, or annual version is preserved.
Default Retention Settings
| Tier | Default | Description |
|---|---|---|
Daily (daily_days) | 7 days | Keep a daily version for the past 7 days |
Weekly (weekly_weeks) | 4 weeks | Keep one version per week for the past 4 weeks |
Monthly (monthly_months) | 12 months | Keep one version per month for the past 12 months |
Annual (yearly_years) | 0 years | Annual retention disabled by default |
With these defaults, you can restore from:
- Any point in the past 7 days (daily granularity)
- Any week in the past 4 weeks (weekly granularity)
- Any month in the past 12 months (monthly granularity)
Compliance Retention
For MSPs subject to data retention compliance requirements (HIPAA, SOC 2, cyber insurance mandates), enable annual retention:
| Annual setting | Effective coverage |
|---|---|
| 3 years | 3 annual snapshots + 12 monthly + 4 weekly + 7 daily |
| 7 years | 7 annual snapshots — common requirement for financial and healthcare data |
Custom Retention Schedules
Override any default tier in the policy:
| Setting | Min | Max | Use Case |
|---|---|---|---|
daily_days | 0 | 365 | Keep daily versions for up to 1 year |
weekly_weeks | 0 | 52 | Keep weekly versions for up to 1 year |
monthly_months | 0 | 60 | Keep monthly versions for up to 5 years |
yearly_years | 0 | 10 | Keep annual versions for up to 10 years |
Setting a tier to 0 disables that tier. For example, if you set daily_days=30 and weekly_weeks=0, only the daily tier is active — no weekly rollups are kept.
Retention and Storage Cost
Longer retention = more storage = higher cost. Approximate storage usage per endpoint at default settings:
| Workload Type | Daily Change Rate | Est. Monthly Storage |
|---|---|---|
| Light office use | 50–200 MB/day | 5–15 GB |
| Active developer | 500 MB–2 GB/day | 20–60 GB |
| Server (file data) | 1–5 GB/day | 40–150 GB |
These estimates assume 30-day daily retention + 12-month monthly retention with compression enabled (typical 40–60% compression ratio on document data).
Use the Storage Estimates tab in the Backups console to preview projected storage cost before committing to a retention policy.
Immutable Retention for Ransomware Protection
Immutable retention prevents backup data from being modified or deleted — even by an MSP administrator — for a defined period. This protects backup integrity against ransomware attacks that target backup infrastructure.
When immutable retention is enabled on a policy:
- Backup objects in Azure Blob Storage are written with a legal hold or time-based immutability policy
- The retention lock cannot be shortened during the immutability period
- Deletion requests are rejected until the immutability period expires
- Backups remain readable and restorable throughout the immutability window
Recommended immutable retention settings for ransomware protection:
| Tier | Recommended Immutability |
|---|---|
| Daily | 14 days |
| Weekly | 8 weeks |
| Monthly | 13 months (one month overlap) |
Retention Cleanup
The retention cleanup timer runs nightly at 3:00 AM UTC. It scans the backup catalog for each tenant and soft-deletes file versions that fall outside the active retention window. Soft-deleted versions are held for 7 days before permanent deletion to allow recovery from accidental policy misconfiguration.
Physical deletion from Azure Blob Storage follows the soft-delete grace period. You will see storage usage decline gradually over 7–10 days after reducing a retention setting, not immediately.
Related Pages
- Backup Policies — Setting retention in a policy
- Storage Tiering — How tier transitions affect cost and restore speed
- Restore Procedures — Point-in-time restore using retained versions