Azure Storage Redundancy for Geo-Clustered Sites

AZ-900 By islever Editorial Last updated

Describe Azure storage services

Short answer

B Recommend Read Access Geo-Redundant Storage (RA-GRS) to ensure data is replicated across regions and readable from both primary and secondary locations simultaneously.

Question

Your company has datacenters in Los Angeles and New York. The company has a Microsoft Azure subscription.
You are configuring the two datacenters as geo-clustered sites for site resiliency.
You need to recommend an Azure storage redundancy option.
You have the following data storage requirements:
✑ Data must be stored on multiple nodes.
✑ Data must be stored on nodes in separate geographic locations.
✑ Data can be read from the secondary location as well as from the primary location
Which of the following Azure stored redundancy options should you recommend?
  1. Geo-redundant storage
  2. Read-only geo-redundant storage Correct Answer
  3. Zone-redundant storage
  4. Locally redundant storage

Key Takeaways

The exam tests knowledge of Azure redundancy tiers, specifically the trap of confusing standard Geo-Redundant Storage (GRS) with RA-GRS regarding read access to the secondary location.

This question evaluates the correct Azure storage redundancy option for geo-clustered sites allowing reads from both primary and secondary regions. The analysis clarifies that Read Access Geo-Redundant Storage (RA-GRS) is the only option supporting active reads in the secondary region.

Common mistake: Learners often choose A (Geo-redundant storage) because they overlook the requirement to read from the secondary location while the primary is still up; standard GRS only allows reads after a failover.

Expert Analysis

Why the Answer Is Correct

The requirement states data must be stored in separate geographic locations (geo-replication) and readable from both primary and secondary locations simultaneously. Read Access Geo-Redundant Storage (RA-GRS) provides exactly this capability by maintaining a readable copy in the secondary region at all times. While the option text uses 'Read-only', it corresponds to RA-GRS, distinct from standard GRS which locks the secondary until failover.

Why the Other Options Are Wrong

Option A (Geo-redundant storage) replicates data to a secondary region but does not allow reads there unless a failover occurs. Option C (Zone-redundant storage) protects against zone failures within a single region, not regional outages. Option D (Locally redundant storage) keeps copies within one availability zone, offering no geographic resilience.

Community Comment Notes

Many users correctly identified B but noted the terminology mismatch, pointing out that Microsoft officially calls it 'Read Access Geo-Redundant Storage'. Comments highlighted that standard GRS prevents secondary reads during normal operations, making RA-GRS the necessary choice for the stated requirements.

Official Reference

https://learn.microsoft.com/en-us/azure/storage/common/storage-redundancy#read-access-geo-redundant-storage-ra-grs

This link opens the official vendor documentation in a new tab.

Exam Strategy

Always check if the question implies simultaneous access to the secondary region. If yes, select RA-GRS. If it only mentions protection against regional failure without specifying concurrent reads, GRS might be sufficient, but look for keywords like 'failover' or 'active-active'.

Frequently Asked Questions

Why is standard Geo-redundant storage (A) incorrect here?

Standard GRS does not allow reads from the secondary region until a failover is triggered. The question requires reads while the primary is active.

Is 'Read-only geo-redundant storage' the official name?

No, the official term is 'Read Access Geo-Redundant Storage' (RA-GRS). The exam option uses 'Read-only' as a synonym for the read-access capability.

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Discussion 64 contributions

Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.

From public community threads 30 of 64

  1. BinuRaj 👍 113
    Answer is correct. Geo-redundant storage (with GRS or GZRS) replicates your data to another physical location in the secondary region to protect against regional outages. However, that data is available to be read only if the customer or Microsoft initiates a failover from the primary to secondary region. When you enable read access to the secondary region, your data is available to be read at all times, including in a situation where the primary region becomes unavailable. For read access to the secondary region, enable read-access geo-redundant storage (RA-GRS) or read-access geo-zone-redundant storage (RA-GZRS).
  2. scab 👍 77
    I think it 's a mistake, it should be "B. Read-access geo-redundant storage" instead of "B. Read-only geo-redundant storage"
  3. rdj_jk 👍 9
    Ans: Option B - RA-GRS. Keywords in the question : "Data can be read from the secondary location as well as from the primary location" Text to refer: "When read access to the secondary is enabled, your application can be read from the secondary endpoint as well as from the primary endpoint. The secondary endpoint appends the suffix –secondary to the account name."
  4. AntonioTech 👍 6 Answered A
    Given the data storage requirements you've provided, the most suitable Azure storage redundancy option would be: A. Geo-redundant storage Geo-redundant storage replicates your data to a secondary region, which is a separate geographic location. This meets the requirement of storing data on nodes in separate geographic locations. Additionally, geo-redundant storage allows you to read data from both the primary and secondary locations, which satisfies the requirement of being able to read data from the secondary location as well. The other options: B. Read-only geo-redundant storage: While this option provides read access to the secondary location, it doesn't store data on nodes in separate geographic locations. C. Zone-redundant storage: This option replicates data within a single region across multiple Availability Zones, but it doesn't meet the requirement of storing data in separate geographic locations. D. Locally redundant storage: This option replicates data within a single datacenter in a region, which doesn't fulfill the requirement of storing data on nodes in separate geographic locations. So, the recommended option is A. Geo-redundant storage.
  5. nhannn 👍 6 Answered B
    B is the correct answer but it should be Read-Access Geo-redundant Storage
Show 25 more comments
  1. Soumyat85 👍 5
    The correct answer is - A. Geo-redundant storage Geo-redundant storage meets all the specified requirements. With geo-redundant storage, data is stored on multiple nodes located in separate geographic locations. It provides redundancy across regions, ensuring high availability and data durability. In addition, data can be read from both the primary and secondary locations, allowing for access to the data even if one location becomes unavailable. B. Read-only geo-redundant storage does not fulfill the requirement that data can be written to and read from both the primary and secondary locations. C. Zone-redundant storage is designed for redundancy within a single Azure region, and it does not satisfy the requirement for geographic separation. D. Locally redundant storage does not meet the requirement of storing data on nodes in separate geographic locations.
  2. Flip46 👍 5
    Answer is correct. B A.Geo-redundant storage; Primary region, 1 Datacenter 3 copies - Geo-replication - Secondary region, 1 Datacenter 3 copies. B.GZRS or RA-GZRS; Primary region, 3 Availability zones within 3 separate Datacenters - Geo-replication - a Secondary region with 1 Datacenter and 3 copies. C.Zone-redundant storage; Primary region, 3 Availability zones within 3 separate Datacenters and separate copy. D.Locally-redundant storage; Primary region in 1 datacenter 3 copies. With a GZRS storage account, you can continue to read and write data if an availability zone becomes unavailable or is unrecoverable. Additionally, your data is also durable in the case of a complete regional outage or a disaster in which the primary region isn't recoverable. https://docs.microsoft.com/en-us/azure/storage/common/storage-redundancy
  3. Tzuyu0613 👍 5
    The Correct answer is B - Read Access Geo Redundant Storage - Normally you can only read from a secondary storage if a failover on the Primary storage is initiated by the customer or Microsoft, but with RA-GRS, you can read from Primary and Secondary Storage, even if the Primary Storage is still up and running. But as Microsoft said, you would have to enable read access for this functionality.
  4. Nxx65 👍 5
    The naming is incorrect, it is RA-GRS "It is names Read Access Geo Redundant Storage " not read only. That would make it R0-GRS.
  5. kahla 👍 4 Answered B
    Requirement 1: "Data must be stored on multiple nodes." This implies data replication for fault tolerance. ✅ All Azure redundancy options replicate data to multiple nodes. 📌 Requirement 2: "Data must be stored on nodes in separate geographic locations." This requires geo-replication—data must be copied to another region, such as Los Angeles ⇄ New York. ✅ Only Geo-redundant Storage (GRS) and Read-access Geo-redundant Storage (RA-GRS) satisfy this. ❌ Locally Redundant Storage (LRS) and Zone-Redundant Storage (ZRS) do not replicate across regions. 📌 Requirement 3: "Data can be read from the secondary location as well as from the primary location." This is read-access from the secondary location, which is only provided by RA-GRS. ✅ RA-GRS: You can read data from the secondary region. ❌ GRS: Secondary region is not readable, only used during failover.
  6. Robdebert 👍 4
    The text "readonly" is misleading, as the requirements also point out to "store" data. According to the official documentation (See link) it is Read-ACCESS instead of Readonly: "For read access to the secondary region, configure your storage account to use read-access geo-redundant storage (RA-GRS) or read-access geo-zone-redundant storage (RA-GZRS).".
  7. MGegruis 👍 4
    With GRS or GZRS, the data in the secondary region isn't available for read or write access unless there is a failover to the secondary region. For read access to the secondary region, configure your storage account to use read-access geo-redundant storage (RA-GRS) or read-access geo-zone-redundant storage (RA-GZRS).
  8. mariza21 👍 3 Answered A
    The correct answer is A. There is no such thing as "Read-Only geo-redundant storage". Four aspects of the redundancy configuration of a storage account determine how your data is replicated and accessible: 1) Local redundancy - your data is always replicated three times within the local or primary region (LRS) 2) Zone redundancy - whether your data is replicated between different zones within the primary region (LRS vs. ZRS) 3) Geo-redundancy - replication within a single "local" region or between a primary and a secondary region (LRS vs. GRS) 4) Read access (RA) - read access to the secondary region when geo-redundancy is used (GRS vs. RA-GRS) The reason you'd pick GRS is because your data is written to your primary node and then replicated to the secondary node. Thus, the system does "write" to both even if the user only writes to one.
  9. derSchweiger 👍 3
    Correct answer is "read access geo redundant storage (RA-GRS)" OR "read access geo redundant zonal storage (RA-GRZS)". It depends on the fact, if the data should be replicated on region 1 on different availability zones or not.
  10. IndyB 👍 3 Answered B
    Key words: "separate geographical locations" & "read" from both locations
  11. rkvijju 👍 2
    The recommended Azure storage redundancy option for the given data storage requirements is Geo-redundant storage (GRS). GRS replicates data to a secondary region located in a different geographic location, providing geo-replication and redundancy. It also allows data to be read from the secondary location in addition to the primary location, which satisfies the requirement of data being readable from both locations. In case of an outage or disaster at the primary location, data can be accessed and used from the secondary location, ensuring high availability and business continuity. Therefore, option (A) Geo-redundant storage is the appropriate choice for configuring geo-clustered sites for site resiliency in this scenario. Option (B) Read-only geo-redundant storage is not suitable because it only allows data to be read from the secondary location and not updated. Option (C) Zone-redundant storage and option (D) Locally redundant storage do not meet the requirement of storing data in separate geographic locations.
  12. brianbanda 👍 2
    he recommended Azure storage redundancy option, based on the given data storage requirements, is Geo-redundant storage (Option A). Geo-redundant storage provides replication of data to another data center in a different region, ensuring that the data is stored on multiple nodes in separate geographic locations. Additionally, it allows for both read and write access to data from both primary and secondary locations. This makes it ideal for geo-clustered sites that require site resiliency. Option B, Read-only geo-redundant storage, only allows for read access from the secondary location and is not suitable for scenarios where data must be written to both locations. Option C, Zone-redundant storage, is not relevant for this scenario as it provides replication of data within a single region. Option D, Locally redundant storage, does not meet the requirement of having data stored in separate geographic locations.
  13. SAFM 👍 2
    Answer B is correct: "Geo-redundant storage (with GRS or GZRS) replicates your data to another physical location in the secondary region to protect against regional outages. However, that data is available to be read only if the customer or Microsoft initiates a failover from the primary to secondary region. However, if you enable read access to the secondary region, your data is always available, even when the primary region is running optimally. For read access to the secondary region, enable read-access geo-redundant storage (RA-GRS) or read-access geo-zone-redundant storage (RA-GZRS)." https://learn.microsoft.com/en-us/training/modules/describe-azure-storage-services/3-redundancy
  14. MAFA56 👍 2 Answered B
    B is correct Read access to data in the secondary region Geo-redundant storage (with GRS or GZRS) replicates your data to another physical location in the secondary region to protect against regional outages. However, that data is available to be read only if the customer or Microsoft initiates a failover from the primary to secondary region. However, if you enable read access to the secondary region, your data is always available, even when the primary region is running optimally. For read access to the secondary region, enable read-access geo-redundant storage (RA-GRS) or read-access geo-zone-redundant storage (RA-GZRS).
  15. appootan 👍 2 Answered B
    New questions that was not from this series of 470 questions. 1. To group relative policy definitions in Azure, you should use Initiatives. I answered subscription groups which is wrong. 2. Scenario for locking for accidental deletion, i answered subscription level. 3. Then there was this question of Window 11, Ubuntu and Mac for using Azure CLI+Azure Portal+Azure Powershell.
  16. ShantanuDutta 👍 2 Answered B
    The difference between GRS and RA GRS is, GRS only allows to be read in the secondary zone in the even of a failover from the primary to secondary while RA GRS allows the option to read in the secondary whenever. In this question, it says read data from secondary whenever it needs. not only failover case. So answer will be B
  17. omsdigital 👍 2 Answered B
    B is correct: Read Access Geo Zone Reduant Storage - 3x copies of data in seperate availability zones data centre - 3x copies in a secondary region (but one location) - Read access in secondary region even if primary region is functional - Read access in secondary region if primary region is down
  18. shahrzadkhb 👍 2 Answered B
    The correct answer would be B. For read access to the secondary region, enable read-access geo-redundant storage (RA-GRS) or read-access geo-zone-redundant storage (RA-GZRS). Link to the reference: https://learn.microsoft.com/en-us/training/modules/describe-azure-storage-services/3-redundancy
  19. mamitos 👍 2
    The problem with the confusion here is that whoever wrote the question here made a mistake. There is no READ-ONLY GRS. The correct name of it is READ-ACCESS GRS. So I guess it is just mispelling cause all the other do not fulfill the criteria, so B is right
  20. Aishu2804 👍 2
    For all those who marked option B as wrong, the term coined here may not be as per the definition (ra-grs or ra-gzrs). But, out of 4 given options, option B suits the best, as u just can't choose anything else to be as possible answer
  21. RVAadmin 👍 2
    The difference between GRS and RA GRS is fairly simple, GRS only allows to be read in the secondary zone in the even of a failover from the primary to secondary while RA GRS allows the option to read in the secondary whenever
  22. Stel0Papad4 👍 2
    Shouldn't be RA-GZRS (Read-Access Geo-Zone-Redundant Storage)? Cause it actually says that it need to be stored in multiple nodes, so it has to has the Zone Redundant aspect in it.
  23. PPV20 👍 2
    Option B. since by default, we cannot read from secondary region unless there is a failover. RA-GRS and RA-GZRS allows read option from secondary region without a failover.
  24. Queenesty 👍 2 Answered B
    Read-only geo-redundant storage (RA-GRS) is the only option that satisfies all the requirements, including read access to the secondary location across geographic regions.
  25. mattygster 👍 2
    Why would the answer not be A, the specifications state it CAN be read, not requesting a read-only based access.

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