AZ, Region Pair

Hi,

In AWS I m not aware of a region/az pairing. One AWS region has multiple AZs, designed to be operationally independent from each other, for high availability and resiliency.

More details here: https://docs.aws.amazon.com/sap/latest/general/arch-guide-architecture-guidelines-and-decisions.html

In Azure, region pair refers more to a disaster recovery strategy: https://build5nines.com/azure-region-pairs-explained/

The only thing that may loosely fit that description is Network Border Group. For instance, the two Local Zones in Los Angeles are part of the same Network Border Group. See: Extend your VPC resources to Local Zones. If you issue the following CLI command, it shows the NetworkBorderGroup.

aws ec2 describe-availability-zones --query AvailabilityZones[?NetworkBorderGroup==\`us-west-2-lax-1\`]
[
    {
        "State": "available",
        "OptInStatus": "opted-in",
        "Messages": [],
        "RegionName": "us-west-2",
        "ZoneName": "us-west-2-lax-1a",
        "ZoneId": "usw2-lax1-az1",
        "GroupName": "us-west-2-lax-1",
        "NetworkBorderGroup": "us-west-2-lax-1",
        "ZoneType": "local-zone",
        "ParentZoneName": "us-west-2a",
        "ParentZoneId": "usw2-az2"
    },
    {
        "State": "available",
        "OptInStatus": "opted-in",
        "Messages": [],
        "RegionName": "us-west-2",
        "ZoneName": "us-west-2-lax-1b",
        "ZoneId": "usw2-lax1-az2",
        "GroupName": "us-west-2-lax-1",
        "NetworkBorderGroup": "us-west-2-lax-1",
        "ZoneType": "local-zone",
        "ParentZoneName": "us-west-2d",
        "ParentZoneId": "usw2-az4"
    }
]

You can also see the ParentZone of the Local Zone. So, that is another kind of pairing.

Hi @suin,

If you are talking about AWS Local Zones, which are localized "Availability Zones" for providing lower latency to certain applications, they do have a parent/child relationship where a Local Zone is paired 1-1 with a primary AWS region. These Local Zones are not exactly the same as a standard Availability Zone and service availability will be zone-dependent.

List of local zones and parent regions can be found here: https://aws.amazon.com/about-aws/global-infrastructure/localzones/locations/

An overview of how Local Zones work can be found here as well: https://docs.aws.amazon.com/local-zones/latest/ug/how-local-zones-work.html

Outside of the Local Zone context, not only are AZs not paired with each other, but the AZ names you are referring to will likely vary between AWS accounts.

For example, in your AWS account versus mine, the AZ us-east-1a might point to a different physical AZ. These remappings are done to prevent the earlier lettered AZs (ex: us-east-1a/b/c) from being flooded with infrastructure requests and leaving the ones farther down (us-east-1d/e/f) under utilized.

The closest thing I can correlate an AZ pairing to would be the mapping of those AZ labels I described above to an Availability Zone ID. These AZ IDs are an account independent mapping to the physical AWS AZs: https://docs.aws.amazon.com/ram/latest/userguide/working-with-az-ids.html. Leveraging these AZ ID mappings can ensure that workloads in different AWS accounts will either be located in the same or different physical location, depending on how you use them.