RAID 6 Triage → When a rebuild looks alive but isn’t

You’ve replaced a drive, started the rebuild, and watched the progress bar inch forward—then freeze. No errors, no warnings, no blinking activity lights. Hours pass. Days, even. The controller still reports “Rebuilding,” yet nothing moves.

This isn’t just a stalled process; it’s a silent negotiation between drives and controller logic. Something below the surface has stopped agreeing about what parity means—and until that’s resolved, your rebuild can’t advance.

What You See

  • Rebuild begins but stalls at 0 % or a low percentage
  • Drive activity lights stay solid or go dark
  • Controller still reports “Rebuilding” or “In Progress”
  • No reported I/O errors or alerts in system logs

What It Likely Means (Why It Happens)

The rebuild engine depends on consistent metadata from every member disk. When a single disk reports unreadable sectors, parity checks can no longer reconcile data across the set. The controller’s logic loop halts to prevent further corruption.

Typical causes include:

  • Silent sector failures — unreadable sectors on “good” drives prevent parity verification.
  • Controller cache mismatch — NVRAM journal or battery-backed cache desynced after a prior power loss.
  • Replacement drive mis-initialized — drive format or block-size mismatch stops rebuild validation.
  • Metadata epoch drift — controller lost version agreement across members.

Essentially: your array didn’t “break”—its internal map lost consensus.

What NOT To Do

  • Don’t assume it just “needs more time.” Stalled rebuilds rarely resume on their own.
  • Don’t restart or reboot during an unresolved rebuild; it can orphan member data.
  • Don’t swap another drive without confirming original slot and layout order.
  • Don’t re-initialize the array. That wipes metadata references entirely.

What You CAN Do

  • Run SMART tests on all drives — not just the replaced ones.
  • Review controller logs for unreadable-sector or cache-flush errors.
  • Capture controller configuration and parity layout using JeannieLite™.
  • Suspend rebuild, snapshot current configuration, and analyze parity consistency.

In RAID 6, a single unreadable sector during rebuild can halt progress indefinitely. Let our engineers analyze the parity state before data loss escalates.

For immediate assistance, call now…

1-800-228-8800

Diagnostic Overview

  • Array Type: RAID 6 (dual parity)
  • Observed State: Rebuild shows “In Progress” with 0%–1% and no movement
  • Symptoms: Low/no drive activity; few new errors in logs; volume accessible or offline depending on controller policy
  • Likely Cause: Silent sector errors on a “good” member; cache/NVRAM journal mismatch; mis-initialized replacement; metadata epoch drift
  • Immediate Action: Stop changes; export config & logs; image members; analyze with JeannieLite™
  • Risk Level: Critical — parity and metadata can be irreversibly altered by forced rebuild/initialize