CostLensBlob Version Cleanup (Azure)
Blob Version Cleanup (Azure)
CostLens flags Azure storage accounts with blob versioning enabled but no lifecycle rule to delete or tier noncurrent versions.
Updated July 20261 min read
CostLens flags storage accounts with blob versioning on but no version-cleanup rule. With versioning enabled and no lifecycle rule, every overwrite keeps the previous version forever — noncurrent versions quietly accumulate storage.
How it works
Storage accounts are enumerated
CostLens lists storage accounts and reads the blob service's isVersioningEnabled flag.
Size + policy are checked
Size comes from the UsedCapacity metric (accounts over ~100 GB); the management policy is checked for a rule that acts on versions.
Savings are estimated
Priced as a conservative fraction (~15%) of storage attributable to accumulated noncurrent versions.
What to do
- Add a lifecycle-management rule that deletes (or tiers to Cool/Archive) noncurrent blob versions after N days.
- Reconsider whether versioning is needed everywhere — disable it on accounts that don't need point-in-time recovery.
Severity levels
| Severity | Estimated monthly savings |
|---|---|
| critical | >$500 |
| high | $100–$500 |
| medium | $20–$100 |
| low | <$20 |
Required permissions
- Detect:
Reader(blob-service properties + Monitor metric + management policy) — see Azure Accounts.
Limitations
- The savings figure is an estimate — actual overhead depends on how often blobs are overwritten.
- Related to Blob Lifecycle Policy, which covers tiering current data.