RAID 5 does not usually fail because a drive stops spinning.
It fails because actions are taken after the first failure — when parity confidence is already compromised.

These Technical Notes exist to document the mechanical realities of RAID 5 behavior during degraded operation: rebuild stalls, silent corruption, metadata loss, and controller-driven failure cascades.

They are not recovery promises.
They are not troubleshooting shortcuts.
They are a diagnostic record of how RAID 5 actually behaves in the field — across enterprise controllers, mixed disk populations, and real-world failure sequences.

Each note isolates a single failure mechanism so administrators, engineers, and decision-makers can understand what is happening before irreversible actions are taken.

What These Notes Are For

The RAID 5 Technical Notes are written to support:

  • Triage decisions after a failure
  • Incident analysis when outcomes don’t match expectations
  • Understanding why “healthy” arrays still lose data
  • Preventing parity overwrite and metadata destruction

They assume familiarity with RAID concepts and focus on cause, sequence, and boundary conditions, not basic definitions.

How to Use These Notes

  • Start with TN-R5-001 for system-level behavior
  • Reference additional notes only as needed
  • Do not apply corrective actions based solely on controller status
  • Treat rebuilds and parity operations as destructive until proven otherwise

These notes are intended to be cited by incident pages, recovery assessments, and internal engineering discussions.

RAID 5 Technical Notes Index