Which Azure Storage Redundancy for Geo-Clustered Sites

AZ-104 By islever Editorial Last updated

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Short answer

B Read-access geo-redundant storage (RA-GRS) replicates data across regions and allows reads from the secondary location without a failover.

Question

Your company has a Microsoft Azure subscription.
The company has datacenters in Los Angeles and New York.
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 question tests whether you know that plain GRS keeps the secondary unreadable until Microsoft-initiated failover, while RA-GRS exposes the secondary for reads — the trap is rejecting option B over its wording.

This AZ-104 question tests Azure storage redundancy choices for a two-region, site-resilient design in Los Angeles and New York. It establishes that read access to a secondary region without waiting for a failover requires read-access geo-redundant storage (RA-GRS), option B.

Common mistake: Option A (geo-redundant storage) is the most common wrong pick: learners argue option B's label says "read-only" instead of "read-access," but GRS alone cannot satisfy the explicit requirement to read from the secondary location.

Expert Analysis

Why the Answer Is Correct

Option B maps to read-access geo-redundant storage (RA-GRS), which replicates data to a paired region — satisfying both the "multiple nodes" and "separate geographic locations" requirements for your Los Angeles and New York sites. Critically, RA-GRS also provides a read-only endpoint for the secondary, so applications can read from the secondary region whether or not Microsoft has initiated a failover. That third requirement is the deciding factor, because it goes beyond plain GRS.

Official Reference

https://learn.microsoft.com/en-us/azure/storage/common/storage-redundancy

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Exam Strategy

When a requirement mentions reading from a secondary location, immediately think RA-GRS (or RA-GZRS); plain GRS only becomes readable after a failover. Don't let a slightly-off option label derail the functional requirement analysis.

Frequently Asked Questions

Why isn't plain geo-redundant storage (GRS) enough for these requirements?

GRS does replicate across geographic locations, but the secondary is inaccessible to users unless Microsoft performs a failover, so it fails the requirement to read from the secondary.

Isn't option B mislabeled as "read-only geo-redundant storage"?

The official product name is read-access geo-redundant storage (RA-GRS). Despite the wording quibble, B is the only option that delivers read access to the secondary region.

More AZ-104 FAQ →

Discussion 80 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 80

  1. Steve1983 👍 104
    B (A: "data will be available to be read-only if Microsoft initiates a failure", so its not RO if its not failed-over) Geo-redundant storage (GRS) As I explained above it helps us in replicating our data to another region which is far away hundreds of miles away from the primary region. It provides at least 99.99999999999999% (16 9's) durability of objects over a given year. GRS replicates our data to another region, but data will be available to be read-only if Microsoft initiates a failure from primary to the secondary region. Read-access geo-redundant storage (RA-GRS) It is based on the GRS, but it also provides an option to read from the secondary region, regardless of whether Microsoft initiates a failover from the primary to the secondary region.
  2. Saravana12g 👍 24
    Answer B. Read-access geo-redundant storage (RA-GRS) It is based on the GRS, but it also provides an option to read from the secondary region, regardless of whether Microsoft initiates a failover from the primary to the secondary region.
  3. pheztux 👍 8
    For those in doubt, here is an exact statement from MS: With an account configured for GRS or GZRS, data in the secondary region isn't directly accessible to users or applications when an outage occurs in the primary region, unless a failover occurs. If your applications require high availability, then you can configure your storage account for read access to the secondary region. When you enable read access to the secondary region, then your data is always available to be read from the secondary, including in a situation where the primary region becomes unavailable. Read-access geo-redundant storage (RA-GRS) or read-access geo-zone-redundant storage (RA-GZRS) configurations permit read access to the secondary region.
  4. sboy 👍 7
    My beef is that there is nothing called (Read-Only Geo-Redundant Storage). It's called RA-GRS, not RO-GRS. I'm going with A on my test today. 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. 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).
  5. rawrkadia 👍 7
    You don't have any access to the redundant data live/without failover in GRS. People need to stop just guessing. Either look it up or lab it.
Show 25 more comments
  1. Wassel_Laouini 👍 5 Answered A
    it's answer A, for everyone that chose answer B, read carefully it says Read Only geo redundant storage, which doesn't exist, it's called Read Access only geo redundant storage, it's a trick question, and for that reason answer A is correct which is the closest to the requirements
  2. ghfalcon7 👍 5
    There is no storage option called read only geo redundant storage, answer should be A, you just enable the Read-access geo-redundant storage (RA-GRS) after you select the GRS option.
  3. chaudha4 👍 5
    Wrong Answer. availability zones will not provide geo redundancy. You need RA-GRS.
  4. allyQ 👍 5
    Read Access Geo Redundant Storage NOT Read 'Only' Geo Redundant Storage
  5. ThePro 👍 4 Answered B
    Answer will be RO-GRS because question states that secondary storage should also be available for read access. This is the difference btwn GRS and RO-GRS, GRS Secondary node is available for read access only if primary is failed.
  6. pkazemei 👍 4
    This is a trick question. I thought A, but then the question says at the end "Data can be read from the secondary location as well as from the primary location". This means the answer is B, because only RA-GRS can do this.
  7. shadyspark 👍 4
    I looked at microsoft docs and could not find "Read only GRS" but "read access GRS" answer should be "A" https://docs.microsoft.com/en-us/azure/storage/common/storage-redundancy.please feel free to correct me
  8. BUDSENA 👍 4 Answered A
    There is no read-only geo-redundant storage. It's called Read Access, it's a trick question. A is the correct answer. B should be correct if it stated the correct name.
  9. Mehedi007 👍 4 Answered B
    "Data can be read from the secondary location as well as from the primary location." Passed the exam on 26 July 2023. Scored 870. Similar question came.
  10. WillHayes 👍 3
    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). For more information, see Read access to data in the secondary region. https://docs.microsoft.com/en-us/azure/storage/common/storage-redundancy
  11. JoePerry42491 👍 3
    This should really be RA-GZRS, as RA-GRS only stores on one node (datacenter) each in both the primary and secondary regions via Locally Redundant Storage (LRS). RA-GZRS would satisfy multiple nodes in the primary region via Zone Redundant Storage (ZRS), and copy to one node in the secondary region via (LRS)
  12. 18c2076 👍 3
    The Correct answer is not actually provided. Correct answer here would be RA-GRS (Read Access Geo-Redundant Storage) Nothing about the description is requesting "read only"
  13. fwp 👍 3
    Your conclusion is not correct, as mentioned in other discussions, as there is only read needed for the secondary zone. So, the correct answer is B.
  14. fiahbone 👍 3 Answered B
    Data can be read from the secondary location as well as from the primary location. This calls for the RA-GRS
  15. Ravikrsoni 👍 2
    A. Geo-redundant storage (GRS): This option meets the requirements. It replicates your data to a secondary region, which is at least 400 miles away from the primary location. It provides read access to the data in the secondary region, allowing you to read from both the primary and secondary locations. B. Read-only geo-redundant storage: While it provides read access to the data in the secondary region, it doesn't meet the requirement of being able to read from both the primary and secondary locations. Therefore, it is not the best fit for the scenario. C. Zone-redundant storage: This redundancy option is designed to replicate data across multiple availability zones within a region for high availability but does not meet the requirement of separate geographic locations. D. Locally redundant storage: This option replicates data within the same region but not across separate geographic locations, so it does not meet the requirements. So, the correct answer is A. Geo-redundant storage (GRS).
  16. yusuf_eb 👍 2 Answered B
    In Azure terminology, Read-Access Geo-Redundant Storage (RA-GRS) is sometimes referred to as "Read-Only Geo-Redundant Storage" because: Secondary Region Access is Read-Only: In RA-GRS, data replicated to the secondary region is accessible but only in read-only mode. This means users cannot modify the data in the secondary location—they can only read it. Write operations are still limited to the primary location. Distinction from Full Read-Write Access: The term "read-only" emphasizes that while you can access data in the secondary region, it’s not a fully writable, independent copy. Changes must still originate in the primary location, and then they’re asynchronously replicated to the secondary. Summary: So, "read-only" simply clarifies that while the secondary location provides access for reading, it’s not intended for active data modification, thus helping maintain data integrity across regions. Correct Answer: B. Read-Only Geo-Redundant Storage (RA-GRS)
  17. ElDakhli 👍 2 Answered B
    RA-GRS allows Read-Only Access to the secondary region without the need for failure in the primary region. However, because data is replicated asynchronously from the primary to the secondary region, the secondary region is typically behind the primary region in terms of write operations. If a disaster were to strike the primary region, it's likely that some data would be lost. The interval between the most recent writes to the primary region and the last write to the secondary region is known as the recovery point objective (RPO). The RPO indicates the point in time to which data can be recovered. The Azure Storage platform typically has an RPO of less than 15 minutes, although there's currently no SLA on how long it takes to replicate data to the secondary region. And note that Azure Files does not support read-access geo-redundant storage (RA-GRS) or read-access geo-zone-redundant storage (RA-GZRS).
  18. Devendra M 👍 2 Answered B
    Read-only geo-redundant storage, officially called Read-access geo-redundant storage (RA-GRS). RA-GRS meets all three requirements: - Multiple nodes: Maintains three copies in the primary region and three in the secondary region. - Separate geographic locations: Replicates data to a geographically distant secondary Azure region. - Reads from both locations: Provides read/write access to the primary and read-only access to the secondary without requiring failover.
  19. Jig77 👍 2
    Correct answer should be 'B'. GRS (Geo-Redundant Storage): Replicates data to a secondary region (typically hundreds of miles away). If the primary region fails, the data can be restored from the secondary region. RA-GRS (Read-Access Geo-Redundant Storage): Works like GRS, but with the additional capability that data can be read from the secondary region. This is useful for scenarios where you may want to access your data even if the primary region is down.
  20. maxmarco71 👍 2
    Answer is C Zone-redundant storage (ZRS) copies your data synchronously across three Azure availability zones in the primary region. For applications requiring high availability, Microsoft recommends using ZRS in the primary region, and also replicating to a secondary region. With ZRS, your data is still accessible for both read and write operations even if a zone becomes unavailable https://docs.microsoft.com/en-us/azure/storage/common/storage-redundancy
  21. NaoVaz 👍 2 Answered B
    I believe the right answer is B) " Read-only geo-redundant storage". In RA-GRS data is stored on multiple Nodes, a copy exists in a different Region, and the "RA-" part assures that data can be read from the secondary region. https://docs.microsoft.com/en-us/azure/storage/common/storage-redundancy#read-access-to-data-in-the-secondary-region
  22. karuppu5610 👍 2
    With GRS or GZRS, the data in the secondary region isn't available for read or write access unless there's 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).
  23. mathyvarnan 👍 2 Answered A
    GPt Says The correct Azure storage redundancy option that meets the requirements is: A. Geo-redundant storage (GRS) Explanation: Geo-redundant storage (GRS) stores data across two geographic locations (regions), which aligns with your requirement to store data in separate geographic locations.
  24. Saurabh_Bhargav 👍 2
    B. RA-GRS Because only this replication option provide read access to Secondary Region even when there is no failure in primary region. In case of GRS, only primary is available until there is no failure
  25. thalasi 👍 2 Answered B
    GRS → secondary is NOT readable RA-GRS → secondary IS readable (read-only) ZRS - Stays within the same geographic region and No cross-region replication LRS - No secondary region

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