You log in to your Synology DSM and see it: “RAID Group Degraded.” Yet, all drives appear green. No drive shows as failed or dropped. What gives?
What’s Really Happening
Synology RAID (especially SHR or Hybrid RAID) can degrade even when all drives pass SMART. The issue often stems from:
- Latency or I/O timeout during boot
- Failed rebuild that left metadata mismatched
- Internal flags marking a drive as unreliable without dropping it
What Not To Do
- Don’t pull and reinsert drives — it may trigger rebuild on the wrong volume
- Don’t run volume repair tools until you check drive logs
- Avoid power cycling repeatedly; it can worsen disk sync states
When To Escalate
- If the degraded message persists across reboots
- If you see “System Partition Failed” in the drive status tab
- If the rebuild never begins or stalls at 0%
What You Can Do
Let Jeannie walk you through a non-destructive check. You’ll know:
- Which disk triggered the flag
- Whether a metadata mismatch or enclosure issue is involved
- If full recovery or external rebuild is the safest option