Bug 2051571

Summary:	Upgrade of RHEL worker nodes from 7 -> 8 should be documented
Product:	[Red Hat Storage] Red Hat OpenShift Data Foundation	Reporter:	Petr Balogh <pbalogh>
Component:	documentation	Assignee:	Anjana Suparna Sriram <asriram>
Status:	NEW ---	QA Contact:	Elad <ebenahar>
Severity:	high	Docs Contact:
Priority:	unspecified
Version:	4.9	CC:	asriram, mmuench, odf-bz-bot
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
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Description Petr Balogh 2022-02-07 14:26:07 UTC

Describe the issue:
We do not describe in our upgrade documentation about upgrade from RHEL 7 to RHEL 8 worker nodes.

I see here:
https://docs.openshift.com/container-platform/4.9/machine_management/adding-rhel-compute.html#:~:text=Adding%20RHEL%207,Platform%20release%20notes.

It's documented that admin should deploy new RHEL 8 nodes and delete old RHEL 7 nodes.

I think that we should at least document the info that when adding new RHEL 8 worker nodes that they should be labeled + maybe info that the nodes should be then deleted one by one, waiting for re-balance to happen to prevent any corruptions to the cluster. As I can imagine if user will just create new nodes and delete all old RHEL 7 worker nodes at once that it might cause some issues/corruptions.

We are mentioning that : RHEL 7 is now deprecated here:
https://access.redhat.com/documentation/en-us/red_hat_openshift_data_foundation/4.9/html-single/planning_your_deployment/index

Describe the task you were trying to accomplish:
Have process for upgrade from RHEL 7->8

Suggestions for improvement:

Document URL:

Chapter/Section Number and Title:

Product Version:
I think this is applicable for all releases since 4.6 to 4.9.

Environment Details:

Any other versions of this document that also needs this update:

Additional information: