Vault Backup Schedule

Note

We are considering a 10-year mandatory retention with incremental backups between weekly full backups.

Backup Plan

Daily / per change
- Incremental backups (only changes since the last backup).
- Retain for 30 days.
- Note: No incremental on the same day as a weekly full.
Weekly
- Full backup every Saturday, named obsidian-YYYY-MM-DD.zip.
- Retain for 9 weeks.
Monthly
- Full backup from the last weekend of the month.
- Retain for 25 months.
Yearly
- Full backup from the last weekend of December.
- Retain for 10 years (our requirement).

Storage Estimation

Assumptions

Vault size = 1 unit.
Full backup = 1 unit.
Incremental backup = ~0.1 unit (10% of vault size, conservative).
Compression ignored for estimation (text compresses well in practice).

Overlap Logic

Monthly vs weekly: In 25 months, ~2 month-end backups overlap with the 9 weekly backups → subtract 2.
Yearly vs monthly: In 10 years, 2 December backups overlap with the 25-month window → subtract 2.
Daily incrementals: 30-day retention minus weekly full days (~4 Saturdays in 30 days).

Calculation

\begin{aligned} Daily incrementals & = (30 - 4) \times 0.1 = 26 \times 0.1 = 2.6 \\ Weekly full & = 9 \\ Monthly full (unique) & = 25 - 2 = 23 \\ Yearly full (unique) & = 10 - 2 = 8 \\ Total (10 years) & = 2.6 + 9 + 23 + 8 = 42.6 \approx 43 vault sizes \end{aligned}

Worst-case (5 Saturdays in 30 days):
$(30 - 5) \times 0.1 = 2.5 \Rightarrow Total \approx 42.5$

Tip

Incremental backups don’t save much storage space in this model, but they significantly reduce bandwidth and backup time for daily operations, since only changes are transferred instead of the entire vault.

Best Practices

Exclude .git: It can be recovered from GitHub; excluding it reduces archive size.
Test restores: Open at least yearly backups as vaults to verify integrity.
3-2-1 rule: Keep 3 copies, on 2 different media, with 1 off-site (e.g., cloud + external drive).
Compression: Use .zip or similar; text and many attachments compress significantly.

Strategies

Full-only: Simpler, but heavier on storage and time.
Incremental + full (recommended): Efficient for daily operations, while full backups ensure reliable restore points.
Hybrid: Local incrementals + off-site fulls (e.g., cloud).

Comparison Table

Strategy	Pros	Cons	Storage Estimate (10 years)
Full-only	Simple, easy to manage, straightforward restore	Heavy on storage and bandwidth, slower backups	~40 vault sizes
Incremental + full	Saves bandwidth and time, granular restores	Slightly more complex restore process	~43 vault sizes
Hybrid	Balance of efficiency and redundancy	Requires multiple tools/locations	~40–45 vault sizes

Restore Example

Scenario: Restore a file from 5 years ago, in month 6, week 3, on a Wednesday.

Steps:

Identify the closest full backup before the target date:
- Use the weekly full from Saturday of week 2 (month 6, year 5).
Apply the incremental backups:
- From Sunday (week 2) through Wednesday (week 3).
- This reconstructs the vault state as of Wednesday.
Verify the restored vault:
- Open it in your system.
- Confirm the target data is present in the expected state.

Formula:

Restore point = Last full backup before target date + All incrementals up to target date

Tip

A backup is only useful if it can be restored. Test periodic restores, especially for yearly archives.