Secondary Disk Not Showing or Missing – Troubleshooting Guide

A SoftRAID Mirror (RAID 1) volume is comprised of a Primary disk and one or more Secondary disks. SoftRAID supports up to 15 secondary disks in a Mirror volume, any of which can be offline or disconnected.

When the volume tile shows ”Missing Secondary Disk”, it means SoftRAID is aware that a secondary disk should be part of this volume, but it is not currently connected or accessible. This status covers three distinct situations.

Situation 1: The Secondary Disk Is Unexpectedly Missing or Has Failed

If you expect all disks to be connected, the secondary disk may have failed or gone offline unexpectedly.

To diagnose:

• Launch the SoftRAID application
• Check whether the secondary disk appears in the disk column
• If it does not appear, remove it from the enclosure and reinsert it firmly
• For HDDs: listen when reinserting — you should hear the disk spin up. Unusual clicking noises indicate failure.
• Check the disk tile for any SMART warnings or Predicted Failure status

If the disk has failed:

• If it is less than 3 years old it is likely under warranty. Contact OWC support.
• Obtain a replacement disk and certify it before putting it into service (Disk menu → Certify Disk)
• Initialize the new disk (Disk menu → Initialize)
• Select the volume tile → Volume menu → Add Secondary Disk

Rebuild optimization: When rebuilding, set volume optimization to Workstation (rebuilds at 50% speed during use, 100% when idle) or Server (always rebuilds at full speed). The other optimization settings are much slower, as they prioritize user performance over rebuild speed.

You can continue using the volume while it rebuilds.

Situation 2: A Secondary Disk Is Intentionally Offline

This status is not always an error — it is sometimes just a notification. A mirror volume will show “Missing Secondary Disk” whenever any secondary is not connected, even if this is intentional.

Example: A 3-disk mirror where the owner removes one disk, stores it off-site, and reconnects it once a month to rebuild. This is a good practice to help protect your data. The volume will show “Missing Secondary Disk” while that disk is away — this is expected behavior and can be ignored.

If the missing secondary disk count is correct — you have one or more disks intentionally offline and are aware of this — you can safely ignore this message.

If the count is not correct — for example, if you replaced a disk in the past but never ran “Remove Missing Secondary Disks” to reset the counter — you can fix this easily:

• Make sure all currently active disks for the mirror are connected
• Volume menu → Remove Missing Secondary Disks

This resets the secondary disk counter so that only the currently connected disks are considered part of the mirror volume.

Situation 3: No Secondary Disk at All

To protect your data, a Mirror volume must have at least one secondary disk connected at all times.

If no secondary disk is connected at all, SoftRAID will notify you that your Mirror has no secondary disk. While your data is not immediately at risk, this volume has no redundancy — a single disk failure will result in data loss.

Reconnect or add a secondary disk as soon as possible. See Situation 1 above for instructions on adding a disk to the volume.

Important Notes

• A mirror with any secondary disk missing is operating without full redundancy — if you have not backed up recently, do so now
• Do not remove additional disks while a rebuild is in progress
• For SMART warnings or disk errors encountered during this process, see our FAQ: “Replace a Disk When SoftRAID Reports Disk Errors”