OWC Gemini Thunderbolt RAID not mounting drives after restart — requires full power drain

Thanks for sharing that — unfortunately, that mirrors my experience almost exactly.

For what it’s worth, I ended up returning my Gemini and replacing it with a Mediasonic 4-bay enclosure. It mounted immediately, survives reboots without needing power removal, and has been flawless so far — at roughly half the price.

What still puzzles me is how OWC continues to sell the Gemini given the mounting and power-state issues multiple users are seeing. Functionally, it behaves like a USB 3 enclosure bridged to Thunderbolt, with none of the reliability or advantages you’d expect from a true Thunderbolt storage device.

After switching enclosures, the problems disappeared entirely, which strongly suggests the Gemini itself is the weak link.

I’m still going back and forth with OWC support trying to get a straight answer on whether this behavior is expected for the Gemini. They consistently avoid answering that question directly. Rather than recommending a refund, they’ve suggested I send the unit to them for testing instead. At this point, it feels like they know this is simply how the device behaves and are unwilling to say so plainly.

My new drive:

Thanks for the suggestions. I want to clarify that this doesn’t appear to be a macOS mounting, permissions, user, or peripheral issue. The problem is hardware-level initialization of the enclosure itself.

The Gemini is fully detected over Thunderbolt (shows in System Information, HDMI works, LEDs light), but the internal drives are not enumerated at all after a restart or cold boot — they are missing from Finder and Disk Utility. No amount of remounting, First Aid, Recovery Mode, user changes, or peripheral removal makes them appear.

The only action that restores the drives is a full power drain of the enclosure (unplugging power and waiting for residual charge to dissipate). This behavior repeats consistently across RAID modes, drive types, cables, and macOS versions.

Because the drives are not visible to macOS at all until the enclosure itself is power-cycled, this strongly points to a firmware or Thunderbolt initialization issue inside the enclosure—not a disk, OS, user account, VPN, or power-strip problem. The OS never sees the drives in the first place, so standard storage troubleshooting steps (First Aid, remounting, Recovery Mode, etc.) don’t apply here.

I’m specifically looking to hear from others who have experienced this behavior with the OWC Gemini (or similar Thunderbolt enclosures), or who can confirm whether this is a known firmware/initialization issue. General storage troubleshooting checklists aren’t helpful in this case because the failure occurs before the drives are even presented to the system.

Yes — unplugging and reconnecting the Thunderbolt cable was one of the first things tested. In that state, the enclosure remains visible as a Thunderbolt device (and HDMI continues to function), but the internal drives do not appear in Finder or Disk Utility. Simply reseating the Thunderbolt cable does not resolve it.

The only action that consistently restores the drives is a full power drain of the enclosure (unplugging AC power and waiting), after which the drives mount normally. A normal restart or shutdown/startup of the Mac causes the drives to disappear again. I believe that this is how the drive was designed and OWC will not admit to it.

No third-party drivers or utilities were installed for this device. This behavior points to a firmware or Thunderbolt initialization issue in the enclosure rather than a macOS or driver issue, which is why I’m looking to see if others have observed the same behavior with the Gemini.

I’ll answer this directly and narrowly, because the issue is not about exploring endless combinations.

Hardware / OS

• Mac: Apple silicon Mac mini M4. Sequoia and Tahoe.

• macOS: Reproducible across multiple recent versions (including clean installs)

Gemini configuration actually tested

• Modes tested:

• Hardware RAID 0

• Independent (JBOD)

• Drives tested:

• 2× SATA SSDs (different brands)

• Single SATA HDD 2.5 drive 500 GIG and 3.5 HDD Seagate 2T HD.

• Bays tested: both bays individually and together

• Formatting: APFS / GUID

• No SoftRAID, no Dock Ejector, no Innergize installed

• No hubs, no docks, direct Thunderbolt connection

• Tested both Thunderbolt ports on the Gemini and multiple all three TB ports on the Mac

• Tested multiple certified Thunderbolt cables

Observed behavior (this is the key point)

• The Gemini always enumerates as a Thunderbolt device (HDMI works, LEDs light)

• After a restart or cold boot, the internal drives do not mount and do not appear in Disk Utility

• Unplugging/replugging the Thunderbolt cable alone does not recover the drives.

• Unplugging/replugging the power cable does nothing, unless....

• Only a full power drain (unplug power, wait for discharge, reconnect) causes the drives to reappear

• The behavior is identical regardless of RAID mode, drive type, or drive count

That means:

• This is not a formatting issue

• Not a driver issue

• Not a SoftRAID issue

• Not a cable or port issue

• Not a macOS user-profile issue

This points to a firmware or initialization fault inside the enclosure, not a configuration problem. Another Gemini owner has documented the same requirement for a full power drain after reboot, which strongly suggests a reproducible hardware issue.

I’m not looking for setup permutations — I’m specifically asking whether others have seen this behavior, or whether OWC has acknowledged a firmware problem that prevents the drives from initializing correctly after restart.

Yes, I have asked them but they have not replied. They tend to ignore you when they know they have an issue that cannot be resolved.