Implement and Manage Storage
This domain covers the configuration, security, and lifecycle management of Azure Storage services. Microsoft weights it at 15–20% of the AZ-104 exam. Expect scenario-based questions requiring you to choose the correct storage account type, redundancy model, access method, or data protection feature given a set of business requirements. You must know exact defaults, limits, and behavioral differences between options, not just conceptual overviews.
Storage Account Types, Redundancy, and Failover
Storage Account Types
| Account Type | Supported Services | Use Case |
|---|---|---|
| Standard general-purpose v2 (GPv2) | Blob, File, Queue, Table | Default choice for most workloads |
| Premium block blobs | Block blobs only | Low-latency blob workloads |
| Premium file shares | Azure Files only | High-performance SMB/NFS shares |
| Premium page blobs | Page blobs only | Unmanaged VM disks |
Key rule: Premium storage uses SSDs and only supports LRS or ZRS redundancy — never GRS or RA-GRS.
Redundancy Options
| Option | Full Name | Copies | Regions | SLA Read | SLA Write |
|---|---|---|---|---|---|
| LRS | Locally Redundant Storage | 3 | 1 zone, 1 region | 99.9% | 99.9% |
| ZRS | Zone-Redundant Storage | 3 | 3 zones, 1 region | 99.9% | 99.9% |
| GRS | Geo-Redundant Storage | 6 | 2 regions (3+3) | 99.9% primary | 99.9% |
| RA-GRS | Read-Access Geo-Redundant | 6 | 2 regions | 99.99% (secondary readable) | 99.9% |
| GZRS | Geo-Zone-Redundant Storage | 6 | 3 zones primary + 1 secondary | 99.9% | 99.9% |
| RA-GZRS | Read-Access GZRS | 6 | 3 zones primary + 1 secondary | 99.9999% | 99.9% |
Secondary endpoint naming: With RA-GRS or RA-GZRS, the secondary read endpoint uses the suffix -secondary (e.g., mystorageaccount-secondary.blob.core.windows.net).
Failover
- Customer-managed failover: You initiate it via portal, CLI, or PowerShell. The secondary becomes the new primary with LRS (geo-replication is lost temporarily). Data loss is possible because replication is asynchronous (check Last Sync Time before failing over).
- Microsoft-managed failover: Only triggered by Microsoft in catastrophic regional failure.
- After failover, you must manually re-configure geo-redundancy (e.g., upgrade back to GRS/GZRS).
- Failover is not supported for accounts with hierarchical namespace (ADLS Gen2) via customer initiation in all scenarios — verify current portal support.
Common Traps
- Exam will offer ZRS as a "geo-redundant" option — it is NOT. ZRS protects only against zone failure within a single region.
- Premium storage types cannot use GRS/RA-GRS — if the scenario requires geo-redundancy + premium, it is not possible with a single account type.
- RA-GRS secondary is read-only — you cannot write to it during normal operation.
- Changing from GRS to LRS is allowed; converting LRS directly to ZRS requires a live migration request or manual data migration.
Blob Tiers and Lifecycle Management
Access Tiers
| Tier | Storage Cost | Access Cost | Min Storage Duration | Retrieval Latency |
|---|---|---|---|---|
| Hot | Highest | Lowest | None | Milliseconds |
| Cool | Lower | Higher | 30 days | Milliseconds |
| Cold | Lower than cool | Higher than cool | 90 days | Milliseconds |
| Archive | Lowest | Highest | 180 days | Up to 15 hours (standard rehydration) |
- Default tier for a new storage account: Hot.
- Tiers can be set at the account level (Hot or Cool only) and at the blob level (all four tiers).
- Archive is only available for block blobs. Archived blobs are offline — you cannot read or copy them without rehydration.
- Rehydration priorities: Standard (up to 15 hours) or High Priority (under 1 hour, higher cost).
Lifecycle Management
Lifecycle management policies automate tier transitions and deletions based on rules. Rules use filters (blob type, prefix, blob index tags) and actions.
Supported actions:
tierToCool,tierToCold,tierToArchive— transition block blobsdelete— delete blobs or blob versions/snapshotsenableAutoTierToHotFromCool— move blobs back to hot when accessed
Key facts:
- Policies are evaluated once per day.
- You can apply rules based on Last Modified, Last Accessed (requires access tracking to be enabled), or Created date.
- Lifecycle policies apply to GPv2 and Blob storage accounts, not premium accounts.
Worked Scenario: A company stores compliance logs that must be accessible immediately for 30 days, then rarely accessed for 60 days, then can tolerate up to 15 hours retrieval delay. Design the lifecycle policy.
Reasoning: Start in Hot (days 0–30) → transition to Cool at day 30 (immediate access, lower cost) → transition to Archive at day 90 (15-hour tolerance). A rule with daysAfterModificationGreaterThan: 30 for cool and daysAfterModificationGreaterThan: 90 for archive satisfies all requirements.
Common Traps
- You cannot move directly from Hot to Archive and skip Cool/Cold — you can, lifecycle policies allow direct transitions.
- Archive blobs cannot be read inline — attempting to download an archived blob fails until rehydration completes.
- Early deletion fees apply if a blob is deleted or moved before the minimum storage duration.
- Lifecycle policies do not apply to premium block blob accounts.
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