RAID Failure and Missing Disks

RAID Failed or Failed Rebuild (RAID 4/5/1+0)

When a RAID array experiences a “FAILED” or “FAILED REBUILD” status, it indicates a critical issue within the array.

Understanding RAID Failure Status

RAID FAILED

A “RAID FAILED” status means one or more drives within the RAID array have malfunctioned or failed. This can result from:

• Physical disk failure
• Data corruption
• Connection problems
• I/O errors across multiple drives
• System crash causing all drives to have I/O errors and be marked “Out of Sync”

FAILED REBUILD

A “FAILED REBUILD” status occurs when SoftRAID attempts to rebuild data on a replacement drive but the process encounters errors or fails to complete.

Common causes:

I/O Errors (most common):

• One or more drives experiences I/O errors during rebuild
• If a drive has I/O errors during rebuild, the rebuild will stop
• SoftRAID will identify which drive has the I/O errors

Multiple Drive Failures:

• If multiple drives have I/O errors during the rebuilding process, it leads to FAILED REBUILD

Implications

Data Loss Risk:

• A RAID FAILED or FAILED REBUILD situation poses serious risk of data loss
• Redundancy measures are compromised or lost
• The array becomes vulnerable without fault tolerance

Critical: BACKUP IMMEDIATELY!

Missing Disk

If a RAID volume is missing a disk, it means:

• The disk failed
• The disk did not power up
• The SoftRAID partition map on the drive was damaged

SoftRAID cannot rebuild a drive with a damaged partition map.

BACKUP IMMEDIATELY!

If Your Volume Won’t Mount

SoftRAID requires a mounted volume to rebuild. If the volume is not mounted, the volume tile will display ”Rebuilding • Waiting for Mount”.

If your volume is not mounting, the volume directory may be damaged. This is a separate issue from the missing disk.

Data recovery may be required:

• Use data recovery applications like Disk Drill or R-Studio
• These tools can recover data from volumes with damaged directories
• Contact SoftRAID support for guidance

Troubleshooting Steps

Step 1: Determine if the Disk is Present

• Launch SoftRAID
• Click on the RAID volume tile
• Check the volume status:
• Does the volume show all disks present?
• Does it show “missing disk”?
• Look at the disk column:
• Are all drives listed?
• Is there a disk present that is not “linked” to the volume?

If all disks show as present: The problem may have corrected itself. Open the SoftRAID log (Utilities menu → View Log) for more information about what occurred.

If the disk is NOT present in the disk column: Skip to Step 4 below.

If the disk IS present but not linked to the volume: Continue to Step 2.

Step 2: Disk Present But Not Linked to Volume

Scenario 2a: Disk links to another volume with same name

Symptom: The disk is present and links to another volume of the same name, and that volume shows “missing disks.”

Action:Contact OWC Technical Support immediately.

This situation may require special handling by support specialists.

Scenario 2b: Disk present with SoftRAID icon but no volume links

Symptom: The disk tile shows the SoftRAID icon but the disk is not linked to any volume.

Action:

• Unmount your volume (Volume menu → Unmount)
• Wait 2 minutes for drives to flush cache
• Remove the disk from the enclosure
• Mount the volume using SoftRAID (Volume menu → Mount)
• If the volume mounts normally:
• Reinsert the disk
• Initialize the disk (Disk menu → Initialize)
• Proceed to Step 3 to add the disk back to the volume

Scenario 2c: Disk shows “?” on disk tile

Symptom: The disk tile shows a question mark icon.

This means: The disk may have failed OR the disk’s partition map is damaged.

Diagnosis:

• Examine the disk tile - Does it show:
• Capacity information?
• Serial number?
• SMART information?
• If the tile shows normal information:
• The partition map is damaged but the drive may be functional
• The disk had data overwritten in the “prohibited” partition map area
• You need to initialize the disk

Important: If your volume is not mounting OR mounting “read only” from macOS, do NOT initialize the disk. Contact OWC Support immediately. If volume mounts normally:

• Unmount your volume
• Wait 2 minutes
• Remove the disk
• Mount the volume using SoftRAID
• If volume mounts normally, reinsert the disk and initialize it
• Proceed to Step 3
• If the disk tile information is mostly empty (no capacity, serial, or SMART data):
• The disk may have failed completely

Action:

• Certify the disk (Disk menu → Certify Disk)
• If certification fails: Replace the disk immediately
• If certification passes: Initialize the disk and verify it shows normal information identical to your other drives
• Proceed to Step 3

Step 3: Add the Disk Back to the Volume

• Select the volume tile for this volume
• Go to Volume menu → Add Disk
• Select the replacement or reinitialized disk
• Check volume optimization settings:
• Server: Rebuilds at 100% speed – volume will be slower during rebuild
• Workstation: Rebuilds at 50% speed during use, 100% when idle – balanced option (recommended)
• Other settings: Will rebuild very slowly, pausing until computer is idle for extended periods
• Monitor the rebuild:
• Check rebuild progress in the volume tile
• Look for I/O counter progress and time remaining
• Ensure rebuild is progressing normally

You can continue using the volume during rebuild, though performance may be reduced.

Step 4: Disk is Missing from Disk Column

The disk does not appear anywhere in SoftRAID’s disk list.

For HDDs (rotating media):

• Launch SoftRAID
• Use Blink Disk Light feature to identify which disks are present:
• Select each disk tile
• Go to Disk menu → Blink Disk Light
• Note the location of each functioning disk
• Identify the missing disk by process of elimination
• Remove and reseat the missing disk:
• Remove the disk from the enclosure
• Inspect the drive connectors for damage
• Firmly reinsert the disk, ensuring it’s fully seated
• Listen for the drive to spin up
• Check if disk reappears:
• If yes: Return to Step 1 or Step 2
• If the disk shows a SMART failure: Replace the disk immediately
• If no: The disk has likely failed – replace it

For NVMe drives:

Blink Disk Light cannot be used with NVMe drives.

Contact OWC Support for assistance identifying which NVMe drive is missing.

RAID 0 Special Considerations

RAID 0 has no redundancy - a missing disk means the volume cannot mount.

If RAID 0 volume won’t mount and disk has failed:

All data on this volume is lost. RAID 0 provides no fault tolerance.

If the disk appears in disk column but isn’t linked to volume:

OWC support specialists may be able to recover your data if you are not fully backed up.

• Contact support immediately
• Do not rely on this - always maintain current backups of RAID 0 volumes

If the disk doesn’t appear in the disk column:

• Use Blink Disk Light to identify remaining disks (HDDs only; contact support for NVMe)
• Remove and reseat the missing disk
• Listen for the drive to spin up
• If the disk reappears and volume mounts:
• BACK UP IMMEDIATELY
• May indicate a bad connection between drive and enclosure
• This should only occur with older enclosures (several years old) or high humidity environments
• Consider replacing the enclosure to prevent future data loss
• If the disk doesn’t reappear:
• The disk has failed
• All data is lost

Important: RAID 0 volumes should be backed up frequently. Any disk failure results in total data loss.

Prevention Tips

To minimize RAID failures:

• Monitor SMART status - Replace drives with predicted failures immediately
• Replace aging drives - Follow POH recommendations (25,000-30,000 hours)
• Maintain backups - RAID is not a backup
• Use quality enclosures - Poor enclosures can cause connection issues
• Avoid hot/humid environments - Keep enclosures well-ventilated and dry
• Handle with care - Physical shock can damage drives
• Use UPS/surge protection - Power issues can corrupt data