Summary

RHOSO 18 documentation provides conflicting guidance on storage requirements for control plane services (Galera, OVN, RabbitMQ), specifically regarding the necessity of local SSDs versus the use of external StorageClasses like ODF.

Description

There is a lack of alignment between different sections of the RHOSO 18 documentation regarding how persistent storage should be provisioned for core technical services.

1. Conflict 1 (Local vs. Standard SC): The Planning Your Deployment guide (Section 3.1.1) states that 5 GB of PVs must be backed by local SSDs for Galera, OVN, and RabbitMQ. However, the Configuring Persistent Storage guide suggests the system is designed to use the Standard OpenShift StorageClass mechanism, which may or may not be local.

1. Conflict 2 (Scope of External ODF): The documentation identifies Red Hat OpenShift Data Foundation (ODF) in External Mode as a supported solution. It is currently unclear if "RHOSO services" in this context refers only to end-user services (Cinder, Glance) or if it includes the control plane databases mentioned above.

Steps to Reproduce

View Performance Requirements: Navigate to the RHOSO 18 Planning Guide Section 3.1.1. Note the explicit mandate: "5 GB of the available PVs must be backed by local SSDs for control plane services such as the Galera, OVN, and RabbitMQ databases."

View Supported Backends: Navigate to the Configuring Persistent Storage Guide. Note that it identifies External ODF as a supported solution for "RHOSO services."

Identify the Gap: Observe that there is no clarification on whether External ODF (non-local) satisfies the "Local SSD" requirement for the control plane, or if the control plane is strictly limited to LVMS-backed local PVs.

Location of Inconsistency

• Planning Guide: Section 3.1.1 (Mandating Local SSDs).
• Configuring Persistent Storage Guide: Chapter 1 (Standard StorageClass and External ODF support).

Requested Changes

• Explicitly define which storage backends are supported for Galera, OVN, and RabbitMQ.
• Clarify if "External Mode ODF" is a supported StorageClass for control plane metadata and stateful services.
• Ensure terminology for "RHOSO services" is consistent (distinguishing between control plane technical services and data plane storage services).