This inefficiency occurs when a blob container intended for long-term or infrequently accessed data continues to store objects in higher-cost tiers like Hot or Cool, instead of using the Archive tier. This often happens when containers are created without lifecycle policies or default tier settings. Over time, storing archival data in non-archival tiers results in avoidable cost without any performance benefit, especially for compliance data, backups, or historical logs that rarely need to be accessed.
Blob storage is billed based on the total volume of data stored per tier (Hot, Cool, Archive), with higher per-GB costs for tiers optimized for frequent access. The Hot tier has the highest storage cost but lowest access latency and transaction cost. Archive tier is the least expensive for storage but comes with higher data retrieval costs and latency. Cool tier sits in the middle. Costs accrue based on the selected tier, regardless of whether the data is actively used.
Transition eligible objects to the Archive tier to reduce long-term storage costs. Implement Azure Blob Lifecycle Management policies to automatically move data to lower-cost tiers based on age or last access time. When migrating existing objects, confirm that the retrieval latency and cost profile of the Archive tier aligns with business needs.
