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Difficulty: Very hardBlob, File, and Disk Storage Solutions

An organization is designing the storage architecture for a new multi-tier financial analytics solution in Azure. The solution has the following design requirements:

* Database logs: The transactional database tier requires a dedicated disk for write-intensive logs. The disk must support up to 80,00080,000 IOPS and sub-millisecond write latency. The logs must survive local hardware failures within a single datacenter, but do not require zone-wide protection.
* Profile images: The web tier requires shared storage for user-uploaded profile images. The storage must survive a zone-wide datacenter outage. Access URLs must be valid for 66 months, and the security team must be able to immediately revoke access to all active URLs in the event of a security breach.
* Audit logs: The compliance tier requires archiving audit logs for 77 years. The audit logs must be immediately readable with sub-second latency when queried, though they are rarely accessed.

Which combination of storage configurations and features should you recommend?

  1. A
    Database logs: A Standard SSD disk configured with Locally Redundant Storage (LRS). Profile images: Azure Blob storage configured with Zone-Redundant Storage (ZRS), using a Service Shared Access Signature (SAS) associated with a Stored Access Policy. Audit logs: Azure Blob storage configured with a lifecycle management policy that moves data to the Archive tier.
  2. Database logs: A Premium SSD v2 disk configured with Locally Redundant Storage (LRS). Profile images: Azure Blob storage configured with Zone-Redundant Storage (ZRS), using a Service Shared Access Signature (SAS) associated with a Stored Access Policy. Audit logs: Azure Blob storage configured with a lifecycle management policy that moves data to the Cool tier.Answer
  3. C
    Database logs: A Premium SSD v2 disk configured with Locally Redundant Storage (LRS). Profile images: Azure Blob storage configured with Locally Redundant Storage (LRS), using an ad-hoc Shared Access Signature (SAS) token. Audit logs: Azure Blob storage configured with a lifecycle management policy that moves data to the Cool tier.
  4. D
    Database logs: A Premium SSD v2 disk configured with Locally Redundant Storage (LRS). Profile images: Azure Blob storage configured with Zone-Redundant Storage (ZRS), using an ad-hoc Shared Access Signature (SAS) token. Audit logs: Azure Blob storage configured with a lifecycle management policy that moves data to the Archive tier.

Answer

The configuration recommending a Premium SSD v2 disk with Locally Redundant Storage (LRS) for database logs, Azure Blob storage with Zone-Redundant Storage (ZRS) using a Service SAS linked to a Stored Access Policy for profile images, and Azure Blob storage with a lifecycle policy moving data to the Cool tier for audit logs.
The configuration recommending a Premium SSD v2 disk with Locally Redundant Storage (LRS) for database logs, Azure Blob storage with Zone-Redundant Storage (ZRS) using a Service SAS linked to a Stored Access Policy for profile images, and Azure Blob storage with a lifecycle policy moving data to the Cool tier for audit logs correctly satisfies all constraints. Premium SSD v2 provides the required performance (80,00080,000 IOPS) and sub-millisecond latencies, ZRS protects the web images from zone-wide datacenter failures, the Stored Access Policy enables immediate token revocation, and the Cool tier provides cost-effective storage while keeping data immediately readable.

Step-by-Step Solution

1
Evaluate the database log storage requirements.
Determine that the transactional logs require a performance tier capable of 80,00080,000 IOPS and sub-millisecond latency (which rules out Standard SSD/HDD and Premium SSD v1, leaving Premium SSD v2 or Ultra Disk). Since it only needs to survive local hardware failures, LRS is the cost-effective and compliant choice.
Premium SSD v2 supports up to 80,00080,000 IOPS and has sub-millisecond latencies, whereas Standard SSDs are limited to much lower IOPS.
2
Evaluate the web tier profile image storage requirements.
Determine that surviving a zone outage requires Zone-Redundant Storage (ZRS). To allow the security team to immediately revoke SAS access URLs without key rotation, the SAS must be a Service SAS associated with a Stored Access Policy.
Stored Access Policies allow changing the expiry time or deleting the policy entirely to invalidate all tokens referencing it. Ad-hoc SAS tokens cannot be revoked unless the storage account key is rotated.
3
Evaluate the compliance tier audit log storage requirements.
Identify that although the logs are rarely accessed (making them candidates for a cooler tier), they must remain immediately readable with sub-second retrieval latency. Move them to the Cool tier rather than the Archive tier.
The Archive tier requires a rehydration process that takes hours, which violates the requirement for sub-second query latency.

Key Concept

Selecting Azure disk types, redundancy configurations, and access policies to balance performance, zone-resilience, cost-tiering, and security constraints.
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Topics

Blob, File, and Disk Storage Solutions

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