D8 Hybrid - RAID 1 HDD Bays 1 & 2 Disconnection Issue

[mikebeirao]

Hi everyone,
I'm experiencing a critical issue with my D8 Hybrid and hoping someone here can help, or at least confirm if this is a known problem.
My Setup:

TerraMaster D8 Hybrid (firmware updated to latest version)
2x Seagate Exos X18 18TB in Bays 1 & 2 (RAID 1)
Connected via USB-C to a Windows 11 PC (Intel i9-14900KF, 64GB RAM)
UPS protected power supply


What happened:
While actively editing video files directly from the RAID 1 volume (F:), I suddenly lost complete access to the drive — no warning, no power interruption, during active read/write operations. The SSD in the separate bay (E:) remained fully accessible throughout.
Symptoms:

F: drive shows "Location not available — device not ready"
All 4 HDD LEDs remain green
Windows Event Log shows repeated Event ID 140 every ~10 seconds: "Failure status: No Media — There is no disk in the drive"
The volume number changed mid-session (HarddiskVolume19 → HarddiskVolume21), indicating multiple disconnection/reconnection cycles happening automatically


What I've already tried:

Rebooted both PC and D8 Hybrid — no change
Tested with a different USB-C cable — no change
Tested on a completely different PC — identical error
Updated D8 firmware to latest version (August 2025) — no change
Physically removed and reseated both drives (temperatures were normal) — no change
Full power off for 15 minutes — temporary partial recovery but subdirectory access still failed
Ran EaseUS Partition Master full scan — no partitions found
Ran TestDisk v7.3 — returned "Partition: Read error"
Verified drive permissions and Windows network services — all correct
Windows Disk Management shows the volume as NTFS with correct 16.37TB capacity, but inaccessible


What I found on this forum:
Reading through existing threads (especially t=7346 and t=9432), it seems like the ASM1352R controller shared between Bays 1 & 2 may be the root cause of this kind of disconnection. Several users reported identical behavior, and in some cases moving drives to Bays 3 & 4 resolved the issue.
Since my drives are in a RAID 1 configuration specifically on Bays 1 & 2, I can't simply move them without breaking the array.

My questions:

Is there a firmware update specifically for the ASM1352R controller (Bays 1 & 2)?
Has anyone successfully recovered access to a RAID 1 array after this type of disconnection?
Is this a known hardware defect eligible for warranty replacement?

The data on the drives should be intact (RAID 1 mirror) but is currently completely inaccessible.
Any help would be greatly appreciated. Thanks in advance!

[MikeZhang]

Your current status:

Windows still shows:
RAID logical volume
Correct capacity (16.37TB)
File system type NTFS

However:
TestDisk cannot read the partition
Windows cannot mount
Previously there were repeated disconnections/No Media

This usually means:
The RAID logical layer is still there, but the underlying I/O has encountered serious read anomalies.

The most crucial step now is to immediately obtain SMART information (most important).

You need to: Power off and remove both drives
Connect them to the computer via SATA cables and check the SMART information to see if any hard drive health issues exist.

[mikebeirao]

Update: SMART Diagnostic Results After Testing Both Drives Individually
Hi,
Following the advice from this thread, I removed both Seagate Exos X18 drives from the D8 Hybrid and tested them individually using an ORICO dual-bay docking station (no RAID) with SeaTools.
Drive 1 — Healthy

Quick Test: Passed
Retired Sectors Count: 100/100 — zero reallocated sectors
Head Health Self Assessment: 100/100
Reported Un-correctable: 100/100 — zero uncorrectable errors
Command Timeout: clean
Conclusion: Drive 1 is in perfect health

Drive 2 — Failed

Quick Test: Failed on second run
Retired Sectors Count: 100/100 — OK
Head Health Self Assessment: 100/100 — OK
Reported Un-correctable: 97/97 — OK
Command Timeout: 32 total timeouts, 14 over 5 seconds, 14 over 7.5 seconds — critical
Conclusion: Drive 2 has serious intermittent read/response failures, consistent with the sudden loss of access during active use

Summary:
The root cause of the disconnection issue appears to be Drive 2 failing intermittently under load, causing the RAID 1 array to drop. Drive 1 is healthy and contains the full mirror copy of all data (10.11 TB used).
Both drives were purchased in June 2025 and are under Seagate's 5-year warranty.

I would also like to flag that the D8 Hybrid failed to handle Drive 2's failure gracefully. Instead of continuing in degraded mode with Drive 1 (as any proper RAID 1 implementation should), the controller dropped the entire array without any warning or LED indication. This defeats the purpose of RAID 1 and should be addressed in a firmware update.

Questions:

What is the recommended procedure to recover and access the data from Drive 1, given that it was part of a hardware RAID 1 array managed by the D8 Hybrid's ASM1352R controller?
Is it safe to insert Drive 1 alone into the D8 Hybrid in SINGLE mode to regain access to the data, or could this cause the controller to reinitialize/format the drive and destroy the data?
Should I attempt data recovery before replacing Drive 2 and rebuilding the RAID?

Any guidance would be greatly appreciated. Thank you!

[MikeZhang]

Sorry for the inconvenience, you may replace HDD2 with a new HDD, it will repair RAID1 automatically, after the process is done, you can access data without problem

[mikebeirao]

Hi Mike Zhang:
I new disc will take 2 weeks to arrive and I need to get access to my data.

After identifying that Drive 2 in my D8 Hybrid had failed (confirmed via SMART diagnostics), I want to share my disappointment with how the D8 Hybrid handled this situation — because frankly, it should never have happened this way.
What the D8 Hybrid did:
When Drive 2 started failing intermittently, the ASM1352R controller simply dropped the entire RAID 1 array without any warning whatsoever. No LED turned red. No notification. No alert of any kind. I was working normally, editing video files directly from the drive, and suddenly lost complete access to all my data — including Drive 1, which was perfectly healthy the entire time.
The irony is painful: I chose RAID 1 specifically to protect my data against drive failure. Instead, a single failing drive made all my data completely inaccessible for an entire day, requiring extensive troubleshooting, third-party tools, and external hardware to diagnose.

What should have happened — and what every proper RAID 1 implementation does:
RAID 1 exists for one reason: fault tolerance. When one drive in a mirrored array begins to fail, the correct behavior is well established and universally expected:

Detect the failing drive early — the controller should monitor SMART data continuously and identify drives showing signs of failure (excessive timeouts, read errors, etc.) before a complete failure occurs
Alert the user immediately — the failing drive's LED should turn red, and if software is available, a notification should be sent. The user needs to know there is a problem so they can act before data is at risk
Switch to degraded mode automatically — the array should continue operating normally using only the healthy drive (Drive 1 in my case), with full read and write access maintained. The user should be able to continue working without any interruption
Allow continued operation in degraded mode — the system should remain fully functional while the user sources a replacement drive, which in real-world situations can take days or even weeks
Rebuild the mirror automatically — once the failed drive is replaced with a new one of equal or larger capacity, the controller should automatically rebuild the RAID 1 mirror in the background, without requiring any manual intervention or data loss

This is standard behavior in any enterprise or prosumer RAID controller — LSI, Adaptec, QNAP, Synology — all handle this correctly. The user keeps working. The data stays safe. The failed drive gets replaced. The array rebuilds. No drama.

What the D8 Hybrid actually did instead:

Drive 2 started failing → no warning, no red LED
Controller panicked and dropped the entire array
Drive 1 (perfectly healthy, containing all the data) became completely inaccessible
No degraded mode, no alert, no graceful handling
User lost an entire day troubleshooting what should have been a simple "replace drive 2" situation

This is not acceptable behavior for a device sold with RAID 1 as a data protection feature. If the controller cannot handle a drive failure gracefully, then RAID 1 on the D8 Hybrid offers a false sense of security.

My request to TerraMaster:
Please address this in a firmware update for the ASM1352R controller. At minimum, the D8 Hybrid should:

Turn the failing drive's LED red when SMART thresholds are exceeded
Continue operating in degraded mode when one drive fails, maintaining full access to data via the healthy drive
Notify the user that the array is degraded and a replacement is needed
Rebuild automatically when a new drive is inserted

Until this is fixed, RAID 1 on the D8 Hybrid cannot be considered a reliable data protection solution.
I hope this feedback helps improve the product for everyone.

[MikeZhang]

The D8 Hybrid doesn't have buzzer so there won't be warning sound when drive fails.

A command timeout doesn't necessarily mean the hard drive is damaged; it's likely caused by a connection problem, which is why the hard drive light isn't red. It's recommended to shut down the D8 Hybrid, remove HDD2, and then power it on. HDD1 should be able to access data normally.

You can insert one new HDD to slot2, and it will start to rebuild automatically.