Exam DP-203 topic 1 question 18 discussion

First, about the Question: What fails? -> The (complete) DataCenter, not the region and not components inside a DataCenter. So, what helps us in this situation? LRS: "..copies your data synchronously three times within a single physical location in the primary region." Important is here the SINGLE PHYSICAL LOCATION (meaning inside the same Data Center. So in our scenario all copies wouldn't work anymore.) -> C is wrong. ZRS: "...copies your data synchronously across three Azure availability zones in the primary region" (meaning, in different Data Centers. In our scenario this would meet the requirements) -> D is right GRS/GZRS: are like LRS/ZRS but with the Data Centers in different azure regions. This works too but is more expensive than ZRS. So ZRS is the right answer. https://docs.microsoft.com/en-us/azure/storage/common/storage-redundancy

This can't be correct. Should be D.

GZRS combines the benefits of both geo-redundant storage and zone-redundant storage. It provides redundancy across both regions and availability zones, ensuring data availability even if a data center fails.

Correct Answer: D

D Redundancy in the primary region Data in an Azure Storage account is always replicated three times in the primary region. Azure Storage offers two options for how your data is replicated in the primary region: Locally redundant storage (LRS) copies your data synchronously three times within a single physical location in the primary region. LRS is the least expensive replication option, but is not recommended for applications requiring high availability or durability. 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.

LRS is the lowest-cost redundancy option and offers the least durability compared to other options. LRS protects your data against server rack and drive failures. However, if a disaster such as fire or flooding occurs within the data center, all replicas of a storage account using LRS may be lost or unrecoverable. To mitigate this risk, Microsoft recommends using zone-redundant storage (ZRS), geo-redundant storage (GRS), or geo-zone-redundant storage (GZRS). Source: https://docs.microsoft.com/en-us/azure/storage/common/storage-redundancy#locally-redundant-storage

The Correct Answer is B - based on microsoft documentation ZRS provides excellent performance, low latency, and resiliency for your data if it becomes temporarily unavailable. However, ZRS by itself might not protect your data against a regional disaster where multiple zones are permanently affected. For protection against regional disasters, we recommend using geo-zone-redundant storage (GZRS), which uses ZRS in the primary region and also geo-replicates your data to a secondary region. https://learn.microsoft.com/en-us/azure/storage/files/files-redundancy#zone-redundant-storage

RA-GRS is an option on top of GRS. So, the regions defined for GRS are the same for RA-GRS

zone-redundant storage (ZRS)

I don't understand why the answer is ZRS. ZRS redundancy is across availability zones, not other region. The question mentioned that "if data center fails in the primary Azure region". Isn't it ZRS will not be available when primary Azure region fails? Correct answer should then be GRS then, which redundancy is across region, and is lower cost compare to GZRS.

According to Microsoft "Locally redundant storage (LRS) replicates your storage account three times within a single data center in the primary region." Therefore, if a the center fails, all three copies will be unavailable. However, according to the condition, the data lake should remain available if a data center fails. Azure Data Lake Gen 2 storage is based on blob storage. There is no separate data redundancy options for the Azure Data Lake Gen 2 comparing to that of blob storage within a storage account. Thereofer, option C is incorrect.

is correct

LRS/ZRS doesnt come to picture if anything needs to available in other regions. so GRS is rite one.

I understood it this way, 1. LRS : single 3-storey building in Frankfurt > Each floor has a data center > if the data center fails then everything is lost 2. LRS: Single 3-storey building in Frankfurt and Berlin, if data in Frankfurt center is lost, then we still have in Berlin Hence it's even cheaper because they are in the same Geolocation

Has the question recently changed? Most of the conversation below is talking about zone failures (Availability Zone) whereas the question is talking about a "primary Azure region" (region). In case of a region failure, would a GRS not be required as the ZRS will protect one if one of the availability zones go down (and not the entire region)?

that the data lake remains available if a data center fails in the primary Azure region, while minimizing costs, you should use geo-redundant storage (GRS) for the storage account. GRS stores 3 copies of the data across 2 regions, so that if a data center fails in the primary region, the data can still be accessed from the secondary region and you only pay for the primary region's storage cost.

Microsoft recommends using ZRS in the primary region for Azure Data Lake Storage Gen2 workloads.