Nutshell Series

Azure Blob Storage Tiers Explained: Hot, Cool, Cold, Archive, and Premium

Manjunath

Azure Blob Storage offers multiple storage tiers that allow you to store data in a cost-effective way
based on how frequently the data is accessed and how quickly it needs to be retrieved.
Choosing the right tier helps balance performance, availability, and cost.

Azure Storage Performance Tiers

Azure Blob Storage provides two performance tiers:

  • Premium performance tier
  • Standard performance tier

Premium Storage Tier

Premium storage is optimized for mission-critical and high-performance applications.
It provides low latency and high throughput.

  • Currently available only for Block Blob storage
  • Uses SSD-based storage
  • Designed for workloads requiring consistent low latency
  • Higher cost compared to standard tiers

Standard Storage Access Tiers

The Standard performance tier (available with GPv2 storage accounts) supports multiple access tiers
that are optimized for different data access patterns.

Hot Storage Tier

Hot storage is optimized for data that is accessed frequently.

  • Lowest access costs
  • Higher storage costs compared to other standard tiers
  • Best for active data and frequently accessed objects
  • Highest availability SLA among standard tiers

Cool Storage Tier

Cool storage is optimized for data that is accessed infrequently and stored for at least 30 days.

  • Lower storage costs than Hot tier
  • Higher access costs compared to Hot tier
  • Slightly lower availability SLA than Hot tier
  • Ideal for short-term backups and disaster recovery data

Cold Storage Tier (New)

Cold storage is designed for data that is rarely accessed but still needs to remain online.
It provides a lower-cost option than Cool storage while maintaining online accessibility.

  • Lower storage costs than Cool tier
  • Higher access costs than Cool tier
  • Minimum storage duration of 90 days
  • Data remains online and accessible without rehydration
  • Ideal for long-term retention data accessed occasionally

Archive Storage Tier

Archive storage is optimized for data that is rarely accessed and stored for long periods.
It provides the lowest storage cost but with higher access latency.

  • Lowest storage cost of all tiers
  • Data is stored offline
  • Highest data access costs
  • Minimum storage duration of 180 days
  • Data retrieval requires rehydration and can take hours

Storage Tier Scope and Limitations

  • The Hot and Cool tiers can be set at the storage account level.
  • The Archive tier cannot be set at the account level.
  • Hot, Cool, Cold, and Archive tiers can be set at the blob (object) level.
  • The Archive tier is available only at the blob level.

Key Considerations When Choosing a Tier

  • Hot tier prioritizes performance and availability.
  • Cool tier trades slightly lower availability and higher access cost for lower storage cost.
  • Cold tier provides lower storage cost while keeping data online.
  • Archive tier minimizes storage cost but requires rehydration and higher access latency.

Summary

  • Premium – High-performance workloads requiring low latency.
  • Hot – Frequently accessed data.
  • Cool – Infrequently accessed data stored for at least 30 days.
  • Cold – Rarely accessed data stored for at least 90 days.
  • Archive – Long-term data stored for at least 180 days with flexible access latency.

By selecting the appropriate storage tier, organizations can significantly reduce costs
while meeting performance and availability requirements.

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