When was the last time anyone reviewed your backup retention policies?
The answer is almost always the same. They were set up when the environment was built, probably by someone who has since moved on. Nobody has looked since. That's a problem, because backup costs don't stay static. They compound. In our experience, backup-related charges can quietly reach eight to ten percent of total Azure spend.
The "Set It and Forget It" Trap
Azure Backup is easy to configure and even easier to ignore. Enable it on a VM, pick a retention policy, move on. The backups run. Restore points accumulate. The bill grows.
The default retention is typically 30 days — reasonable for most workloads. But we regularly see organisations where someone changed it to 90 days, 365 days, or 99 years. Usually because the answer to "how long should we keep backups?" was "better safe than sorry."
That instinct is understandable. But it has a cost that compounds every single day.
How Backup Costs Compound
Unlike a VM that costs the same this month as last month, backup costs are almost certainly higher this month. Every day, new recovery points are created. If retention is longer than needed, old points stick around. The storage footprint grows in one direction: up.
A single VM with 500GB of data at 30-day retention reaches a steady state. At 365-day retention, it takes a full year to stabilise, and the total stored data is dramatically larger. Now multiply that by every VM, database, and file share in your estate.
Common Patterns We Find
Dev/Test with Production-Grade Retention
The most common one. Production has 90-day retention for compliance. The same policy gets applied to dev and test because it was easier to use the same template. Why keep 90 days of dev backups? If a dev VM fails, you rebuild it. Seven days is generous.
SQL Databases with Excessive Long-Term Retention
Azure SQL has built-in point-in-time restore with seven-day default retention. Many organisations also configure long-term retention policies keeping weekly, monthly, and yearly backups. If there's no specific compliance driver, you're paying for storage you'll never use.
File Share Backups Duplicating Other Solutions
Azure File Shares backed up through Azure Backup while the same data is replicated by a third-party product, or originates from a source with its own backup. Double protection sounds prudent until you're paying twice for the same capability.
Backing Up VMs Already Replicated for DR
Disaster recovery replication and backup serve different purposes. Some workloads genuinely need both — but some only need one. If a VM is replicated to a secondary region and the only recovery scenario you care about is regional failure, daily backup might be unnecessary. Match the protection to the actual risk.
The Soft Delete Surprise
Azure Backup has soft delete enabled by default. When you delete backup data, it's retained for 14 additional days. This means your actual retention is always 14 days longer than your policy says. If you're cleaning up and expecting immediate savings, they won't appear for a fortnight.
Where the Savings Are
- Reduce dev/test retention to 7 days. Almost never a reason for more.
- Review any policy over 90 days. Confirm there's a documented compliance requirement.
- Check for duplicate protection. Workloads protected by both backup and DR replication — do they need both?
- Audit file share backups. Ensure the data isn't backed up through another mechanism.
- Review SQL long-term retention. No compliance driver? Built-in seven-day restore may suffice.
Why This Catches People Out
Backup costs don't show up as a single visible line item like a large VM. They're distributed across per-instance fees, storage charges, and sometimes multiple vaults and subscriptions. When we run a full analysis, clients are regularly surprised at the aggregate number.
Retention is the lever that controls growth. Every day you don't need is a day of storage you're paying for across every protected resource. It adds up faster than anyone expects.
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