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Azure Cache for Redis - Zone Redundancy

Rajiv Bansal 141 Reputation points
2023-12-01T10:37:05.81+00:00

I want to turn on Zone redundancy for Azure Cache for Redis with two Availability zones. SKU used is Premium tier. I have selected Availability Zones: Zone1 and Zone2. What is the minimum number of replicas to be set: 1, 2 or 3.

Documentation suggests that Azure always create 1 replica (secondary) and the architecture diagram shows that this 1 replica is created in the same Availability Zone. Additionally we can create two more replicas which will be created in different availability zones. What is confusing and not clear is - if Availability Zone is switched on, is the first replica created in different availability Zone or the same as the primary.

Azure Cache for Redis
Azure Cache for Redis
An Azure service that provides access to a secure, dedicated Redis cache, managed by Microsoft.
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  1. TP 78,271 Reputation points
    2023-12-01T12:21:07.4433333+00:00

    Hi Rajiv,

    Answers below:

    I want to turn on Zone redundancy for Azure Cache for Redis with two Availability zones. SKU used is Premium tier. I have selected Availability Zones: Zone1 and Zone2. What is the minimum number of replicas to be set: 1, 2 or 3.

    A: Minimum number of replicas is 1 since there will only be two Availability Zones.

    ... if Availability Zone is switched on, is the first replica created in different availability Zone or the same as the primary.

    A: The replica will be created in different Availability Zone than the primary. You may check this after creating your zone-redundant cache. In sample screenshot below, you can see there are two nodes, and they are in different Availability Zones:

    qna azure cache for redis zone redundant sample1

    Below screenshot is for 2 shards (four nodes), again notice that they are spread across availability zones:qna azure cache for redis zone redundant sample2

    Please click Accept Answer and upvote if the above was helpful.

    Thanks.

    -TP

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  1. ShaktiSingh-MSFT 13,826 Reputation points Microsoft Employee
    2023-12-01T12:09:04.1166667+00:00

    Hi

    Welcome to Microsoft Q&A forum.

    As I understand, you need some clarifications on Azure Cache for Redis Zone Redundancy.

    A Premium cache has one primary and one replica node by default. To configure zone redundancy for more than two Availability Zones, you need to add more replicas to the cache you're creating.

    Zone redundancy is available only in Azure regions that have Availability Zones. See Azure regions with Availability Zones for the latest list.

    Checking more on this, will get back to you.

    Thanks

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