What does the disk status Degraded mean for RAID management?

In FortiAnalyzer RAID management, a Degraded status specifically indicates that the RAID array has lost one or more of its member hard drives. Despite the loss of a drive, the array remains operational, albeit without its full redundancy. The system can continue to handle read and write requests by using the remaining drives and parity data (for RAID levels like 5 or 6). This state is a critical alert that the array's fault tolerance is compromised and requires immediate attention, typically by replacing the failed drive.

A: This description corresponds to the Inactive status, where a drive is explicitly taken offline and is no longer part of the RAID volume.

C: This describes the Rebuilding status, which is the process of restoring data to a new replacement drive to return the array to an Optimal state.

D: While invalid parity data is a critical error, the Degraded status is specifically triggered by a missing or failed drive, not by a parity data validity check.

1. FortiAnalyzer Administration Guide 7.4.2

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System Information widget > RAID Status. The guide explicitly defines the RAID statuses:

Degraded: "One or more drives are missing from the FortiAnalyzer unit."

Rebuilding: "The device is writing data to the disk to restore the volume to an optimal state."

Inactive: "The hard drive is no longer being used by the RAID controller."