Cool Tier for Azure Blob Storage
Purpose: The cool access tier is intended for data that is accessed less frequently but still requires rapid access when needed. It offers a cost-effective solution for storing infrequently accessed data for at least 30 days.
When to Use Cool Tier
- Data that is accessed infrequently (e.g., once every 30 days).
- Data that needs to be available for immediate access when requested.
- Backup data, older data archives, or disaster recovery files.
- Content that is not actively used but must be retained for a period.
Key Characteristics
- Lower Storage Costs: Significantly lower per-gigabyte storage costs compared to the Hot tier.
- Higher Access Costs: Transaction and data retrieval costs are higher than the Hot tier.
- Minimum Duration: Data stored in the Cool tier must be retained for a minimum of 30 days. If deleted or moved to another tier before 30 days, a prorated charge for 30 days will apply.
- Availability: High availability, similar to the Hot tier.
Pricing Considerations
When choosing between Hot and Cool tiers, consider the trade-off between storage costs and access costs. For data that you'll access often, Hot tier is more economical. For data that sits idle for extended periods but needs to be readily available when accessed, Cool tier offers substantial savings.
Below is a simplified representation of cost factors. For exact pricing, please refer to the official Azure Blob Storage pricing page.
| Factor | Hot Tier | Cool Tier |
|---|---|---|
| Storage Cost ($/GB/month) | Higher | Lower |
| Transaction Costs (per operation) | Lower | Higher |
| Data Retrieval Cost ($/GB) | Lower | Higher |
| Minimum Duration | None | 30 days |
How to Use Cool Tier
You can set the access tier for blobs when you upload them or change the tier of existing blobs.
Setting the tier during upload (using Azure CLI):
az storage blob upload \
--account-name \
--container-name \
--name \
--file \
--tier Cool \
--auth-mode login
Changing the tier of an existing blob (using Azure CLI):
az storage blob set-tier \
--account-name \
--container-name \
--name \
--tier Cool
You can also manage access tiers through the Azure portal, Azure Storage Explorer, or other Azure SDKs.
Related Services and Features
- Hot Tier: For frequently accessed data.
- Archive Tier: For data rarely accessed and requiring the longest retrieval times.
- Lifecycle Management: Automate tiering and deletion policies.
- Blob Storage Performance Tiers: Overview of performance and cost options.
Understanding and utilizing the different access tiers in Azure Blob Storage is crucial for optimizing costs and performance for your data storage needs.
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