Hi Azure Sup Welcome to Microsoft Q&A, Thank you for posting your query here!
Yes, you are right, By default all the images do not support high availability repositories.
To use the Azure Red Hat Update Infrastructure (RHUI) for Red Hat Enterprise Linux (RHEL) High Availability on RHEL 8, you can create a Red Hat Enterprise Linux VM from an Azure Marketplace PAYG image which supports High Availability repositories and use Azure-hosted RHUI. The PAYG images already have the correct configuration to connect to Azure RHUI.
Please refer the below document to check the list of RHEL 8 images which support High Availability repositories:
If you use an image that is hardened by you, below command will list all available repositories and if you can see High Availability repo listed, then you will be able to access it:
Command : #sudo yum repolist
For example, RHEL-SAP-HA supports the HA repos:
Hope this is helpful!
Kindly let us know if the above helps or you need any further assistance.
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-Ekta