DEV Community

Cover image for Taming S3 Versioning Before It Blows Up Your Bill
Aaron Rose
Aaron Rose

Posted on

Taming S3 Versioning Before It Blows Up Your Bill

#aws #s3 #devops #cost

Problem

It starts quietly. Someone turns on versioning in an S3 bucket to protect against accidental deletes. A year later, Finance notices the bill has doubled, maybe tripled. Nobody touched the storage class, nobody added new buckets. So what happened?

Every time a file was updated, S3 kept the old version. One key document ballooned into hundreds of hidden copies. Multiplied across thousands of objects, the bucket was now more history book than working archive.

The team is baffled. They thought S3 was “cheap and infinite.” Now it’s an uncontrolled cost center. Versioning sounds like a safety net. In reality, it can become a hidden surcharge that creeps up month after month until it hits the radar of Finance.

Clarifying the Issue

This isn’t about S3 storage being expensive. It’s about unseen growth from versioning. Without policies, versioning piles up old data endlessly:

  • Hidden duplicates: Every update creates another copy, even for trivial changes.
  • Unclear ownership: Teams forget who enabled versioning in the first place.
  • Opaque reporting: AWS bills don’t spell out “versioning cost.” It’s just GBs and dollars.

The result: cost surprises with no single owner.

Why It Matters

S3 is often the backbone of a company’s cloud storage. When costs spiral here, it raises alarms across Finance, Security, and Operations. Unchecked versioning:

  • Eats into budget margins.
  • Wastes engineer hours during audits.
  • Creates distrust in the “cheapness” of cloud storage.

In short: versioning without guardrails undermines trust and predictability.

Key Terms

  • S3 Versioning: A feature that stores every version of an object whenever it’s modified or deleted.
  • Lifecycle Policy: Rules that archive or delete objects (including old versions) after a set time.
  • Storage Classes: Different cost tiers in S3 (e.g., Standard, Glacier, Intelligent-Tiering).

Steps at a Glance

  1. Audit the bucket: Count how many versions exist per object.
  2. Analyze costs: Break down storage by current vs. non-current versions.
  3. Set lifecycle rules: Expire old versions after a set retention period.
  4. Move to cheaper classes: Send rarely accessed versions to Glacier or Intelligent-Tiering.
  5. Monitor regularly: Add alerts so versioning costs don’t creep up again.

Detailed Steps

  1. Audit the bucket: Count how many versions exist per object. Use the AWS CLI to surface hidden versions: 
   aws s3api list-object-versions \
       --bucket my-bucket-name \
       --query 'Versions[].{Key:Key,Size:Size,IsLatest:IsLatest}'
Enter fullscreen mode Exit fullscreen mode

Example scenario: Imagine a single 10 MB .csv file updated daily. After a year, that’s 365 versions — 3.65 GB of storage for what still looks like “one file.” Without lifecycle rules, that’s money leaking silently.

  1. Analyze costs: Break down storage by current vs. non-current versions. Cost Explorer will help you chart growth, but S3 Storage Lens gives deeper visibility: 
   aws s3control describe-storage-lens-configuration \
     --account-id 123456789012 \
     --config-id my-dashboard
Enter fullscreen mode Exit fullscreen mode

In Cost Explorer, filter by Usage Type values like StandardStorage (current versions) and NoncurrentVersionStorage (old versions) to see exactly where the growth is hiding.

  1. Set lifecycle rules: Expire old versions after a set retention period. Create a simple policy (example: delete after 90 days): 
   {
     "Rules": [
       {
         "ID": "ExpireOldVersions",
         "Status": "Enabled",
         "NoncurrentVersionExpiration": {
           "NoncurrentDays": 90
         }
       }
     ]
   }
Enter fullscreen mode Exit fullscreen mode

Apply it to your bucket:

   aws s3api put-bucket-lifecycle-configuration \
     --bucket my-bucket-name \
     --lifecycle-configuration file://lifecycle.json
Enter fullscreen mode Exit fullscreen mode

Console note: In the AWS Management Console, these settings live under the Management tab of the bucket.

  1. Move to cheaper classes: Send rarely accessed versions to Glacier or Intelligent-Tiering. Example policy: 
   {
     "Rules": [
       {
         "ID": "ArchiveOldVersions",
         "Status": "Enabled",
         "NoncurrentVersionTransitions": [
           {
             "NoncurrentDays": 30,
             "StorageClass": "GLACIER"
           }
         ]
       }
     ]
   }
Enter fullscreen mode Exit fullscreen mode
  1. Monitor regularly: Add alerts so versioning costs don’t creep up again. Set CloudWatch or Budget alarms to flag anomalies early: 
   aws budgets create-budget \
     --account-id 123456789012 \
     --budget file://s3-versioning-budget.json
Enter fullscreen mode Exit fullscreen mode

Conclusion

Versioning is powerful insurance, but it’s not free. Without guardrails, it quietly becomes a budget sink. The fix isn’t to turn it off — it’s to manage it deliberately. Audit, set lifecycle policies, and monitor. That’s how you keep versioning as a safety net instead of a financial trap.

Aaron Rose is a software engineer and technology writer at tech-reader.blog and the author of Think Like Genius.

Top comments (0)