Blob Tiers & Lifecycle
Hot · Cool · Cold · Archive · Rehydration · Lifecycle policies
Practice questions for this topic →
Access tiers
| Tier | Minimum period | Access | Use for |
|---|---|---|---|
| Hot | — | Immediate | Active data |
| Cool | 30 days | Immediate | Infrequent, short-term backup |
| Cold | 90 days | Immediate | Rare access with fast retrieval |
| Archive | 180 days | Offline: rehydrate first | Long-term retention, compliance |
Early deletion charges apply before the minimum period. Tiers apply to block blobs only. Smart tier automatically moves data between hot, cool and cold. Storage capacity limits are per account, not per tier.
Archive rehydration
| Item | Detail |
|---|---|
| Methods | Copy Blob to a new blob in hot, cool or cold (different name), or Set Blob Tier to change the blob itself |
| Standard priority | Default; up to 15 hours for objects under 10 GB |
| High priority | May finish in under an hour for objects under 10 GB; costs more; you can raise a pending request to High |
| Throughput limit | 10 GiB per storage account per hour with priority retrieval (account level, not per blob) |
| Snapshots and versions | Can't be rehydrated directly: copy to a new blob in an online tier |
| Cross-account copy | Allowed from service version 2021-02-12 when the destination account is in the same region |
| Notification | Configure Event Grid to fire an event when rehydration completes |
Lifecycle management
- Rules move blobs to cooler tiers or delete them by age or last access, filtered by prefix or blob index tags.
- The Last accessed condition works only if access time tracking is enabled, and the portal offers it for block blobs. Conditions are Creation Time, Last Modified Time and Last Accessed Time; a rule can also move a blob back from cool to hot immediately when it's accessed.
- Timing: new or edited rules can take up to 24 hours to take effect and start; the policy then runs once per day. Supported for block and append blobs in general-purpose v2, premium block blob and Blob Storage accounts; $logs and $web containers are unaffected. Filters (path prefix, blob index tags) combine with AND and can't exclude.
Exam Tips
Tick each tip once you can answer it without looking.
“Keep 7 years for compliance, read maybe once a year, lowest cost” → Archive tier. Trap: Hours to rehydrate.
“Rarely accessed but must be readable within seconds” → Cold tier. Trap: Archive is offline.
“Automatically move blobs to cool after 30 days without access” → Lifecycle management + last access tracking.
“Deleting archived data after 60 days” → Early deletion charge for the remaining 120 days.
“Need an archived blob urgently” → High-priority rehydration.
“Unknown access patterns; avoid managing tier rules” → Smart tier.
“Can't set access tier on append/page blobs” → Tiers apply to block blobs only.
“How long standard-priority rehydration takes” → Up to 15 hours for objects under 10 GB. Trap: The 10 GiB per hour limit applies per storage account, not per blob.
“Faster rehydration of an urgent archived blob” → High priority: may finish in under an hour for objects under 10 GB, at higher cost; you can raise a pending request to High. Trap: Limited to 10 GiB per storage account per hour.
“Read an archived snapshot or previous version” → Copy it to a new blob in an online tier with Copy Blob. Trap: Archived snapshots and versions can't be rehydrated directly.
“Be notified when rehydration completes” → Event Grid event (for example to trigger an Azure Function). Trap: Check status with Get Blob Properties.
“Copy an archived blob to another storage account” → Allowed when the destination is in the same region (service version 2021-02-12 or later); the destination needs a different name. Trap: Same-account copy is also supported.
“Lifecycle policy timing” → Up to 24 hours to take effect and start; then runs once per day. Trap: Last-accessed rules need access time tracking enabled and block blobs.
“What lifecycle rules can act on” → Current versions, previous versions and snapshots; filters by prefix and blob index tags combine with AND and can't exclude. Trap: Supported for block and append blobs in GPv2, premium block blob and Blob Storage accounts.