retention-policies

name	retention-policies
description	Daily/weekly/monthly/yearly retention — GFS, archive tier

Retention Policies

When to use this skill

• Long-term compliance retention
• Cost optimization on retention

Key concepts

• Grandfather-Father-Son (GFS): N daily + N weekly + N monthly + N yearly.
• Long-term yearly retention can be moved to Archive tier for low cost / slow restore.
• Retention applies per recovery point — changing policy doesn't expire old points immediately.
• Compliance commonly requires 7y/10y on yearly — model the cost.
• Soft delete keeps deleted points an extra 14 days minimum by default.

Azure CLI examples

az backup policy set -g <rg> --vault-name vault-prod --policy <policyJson>

Common pitfalls

• Setting 10y retention on daily backups — massive vault cost.
• Forgetting archive tier rehydrate time (~hours) for restores.
• Migrating to a shorter policy and not understanding expiration semantics.

References

• Microsoft Learn: search for "Retention Policies Azure VM" on https://learn.microsoft.com

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