Problem Statement

When users expand the underlying disk block device for RHCOS nodes, the system partition (/sysroot) does not automatically grow on restart to utilize the newly available space. This leaves unused disk capacity and creates a poor user experience, as the expected behavior is for the partition to automatically fill the expanded disk. We currently tell users to reprovision.

User Impact

• Unclear what procedures are required to utilize expanded capacity
• Risk of filling filesystem unexpectedly
• Confusion about proper procedures, especially with LUKS-encrypted partitions
• Reprovisioning control plane nodes is not a simple task and adds risk to the process

Proposed Solution

Improve the user experience through either:

1. Code solution: Implement reliable automatic partition growth on boot (or user-initiated via machineconfig) that handles standard and LUKS-encrypted partitions
2. Documentation solution: Provide clear, tested procedures for manual partition expansion with specific guidance for LUKS scenarios

Acceptance Criteria

• Clear UX for disk expansion scenarios
• LUKS-encrypted partition scenarios addressed
• Solution is tested and reliable
• Documentation reflects actual behavior and procedures