Azure Storage Tiers: Hot, Cool, Cold, and Archive

Why tiers exist

Not all data gets accessed at the same rate. A user’s profile photo gets loaded on every login. A backup from three years ago might never be accessed unless something goes wrong. Charging the same rate for both is wasteful.

Azure solves this with access tiers. You pay less per gigabyte to store data in colder tiers, but pay more per operation (read, write, retrieve) when you access it. This mirrors real-world storage: cheap tape archives are slower and harder to access than fast spinning disks.

The four tiers explained

Hot tier

Hot is the default tier for new storage accounts. It has the highest storage cost per gigabyte but the lowest access cost. Use hot for data you read or write frequently — active application data, assets served to users, or any data where reads happen daily.

Cool tier

Cool costs less to store than hot, but more to access. Data in cool tier must be stored for at least 30 days — if you delete or move a blob before 30 days, you still pay for 30 days of cool storage. Use cool for data you access infrequently but need to access quickly when you do — monthly reports, short-term backups, data awaiting processing.

Cold tier

Cold was added in 2023 and sits between cool and archive. It’s cheaper to store than cool, more expensive to access, and has a minimum storage duration of 90 days. Use cold for data you access rarely — quarterly or less — but still need to retrieve without a long wait. Long-term backups and compliance archives that you occasionally need to inspect are good fits.

Archive tier

Archive is the cheapest storage tier by far, but blobs in archive are completely offline. You cannot read them directly. To access an archived blob, you must first rehydrate it to hot or cool tier — a process that can take up to 15 hours for standard priority rehydration. Archive has a minimum storage duration of 180 days.

Use archive for data you’re legally required to keep but genuinely never expect to need — compliance records, raw data after it’s been processed, or old backups retained for disaster recovery purposes.

Real cost comparison (East US, as of early 2026)

Prices vary by region. These approximate figures for East US illustrate the trade-off structure:

A concrete example: if you store 10 TB of data that you read once a year (like annual tax records), archive tier costs about $10/month. Hot tier for the same 10 TB costs about $180/month. That’s $1,680 per year saved for data you access once.

Always check the Azure pricing page for current rates in your region — prices change and vary by region.

Setting and changing tiers with Azure CLI

# Set the default access tier on a storage account (hot or cool only)
az storage account update \
  --name mystorageaccount123 \
  --resource-group my-storage-rg \
  --access-tier Cool

# Set a single blob to cool tier
az storage blob set-tier \
  --account-name mystorageaccount123 \
  --container-name backups \
  --name 2026-01-31-backup.tar.gz \
  --tier Cool \
  --auth-mode login

# Set a blob to archive tier
az storage blob set-tier \
  --account-name mystorageaccount123 \
  --container-name backups \
  --name 2024-01-31-backup.tar.gz \
  --tier Archive \
  --auth-mode login

# Rehydrate a blob from archive to hot (standard priority)
az storage blob set-tier \
  --account-name mystorageaccount123 \
  --container-name backups \
  --name 2024-01-31-backup.tar.gz \
  --tier Hot \
  --rehydrate-priority Standard \
  --auth-mode login

# Rehydrate with high priority (faster, costs more)
az storage blob set-tier \
  --account-name mystorageaccount123 \
  --container-name backups \
  --name 2024-01-31-backup.tar.gz \
  --tier Hot \
  --rehydrate-priority High \
  --auth-mode login

# Check rehydration status
az storage blob show \
  --account-name mystorageaccount123 \
  --container-name backups \
  --name 2024-01-31-backup.tar.gz \
  --auth-mode login \
  --query "properties.rehydrationStatus"

When a blob is rehydrating from archive, the rehydrationStatus property shows rehydrate-pending-to-hot or rehydrate-pending-to-cool. Once complete, it disappears and the blob is accessible.

Account-level tier vs. blob-level tier

There are two places to set a tier:

1. Account-level default — set to hot or cool. This is the tier applied to any new blob that doesn’t have its own tier set.
2. Blob-level override — set on individual blobs using az storage blob set-tier. This overrides the account default for that specific blob.

Archive is only available at the blob level. You cannot set an entire account to archive tier. To move many blobs to archive automatically over time, use lifecycle management policies (covered in the next page).

Choosing the right tier for your data

Here’s a practical decision framework:

• Accessed daily or weekly: Hot
• Accessed monthly, short-term backup (under 90 days): Cool
• Accessed rarely, longer-term backup (90 days to 1 year): Cold
• Retained for compliance, almost never accessed (over 180 days): Archive

If you’re unsure about access patterns, start with hot and let lifecycle management (described in the next page) automatically move data to colder tiers as it ages. This approach is safer than guessing upfront and finding that archive blobs get accessed more than expected.