TerraMaster Forum

Hello,
I am trying to determine whether the problem I am experiencing with my TerraMaster D5-300C is related to the DAS itself, the NAS USB implementation, or a firmware/compatibility issue.

I have tested the D5-300C with two different NAS systems:
ASUSTOR AS5004T
QNAP TS-231P

I also have a second TerraMaster DAS:
TerraMaster D4-320

The results are quite clear: the D4-320 works correctly on both NAS systems, while the D5-300C has a problem specifically with the ASUSTOR AS5004T.

1. ASUSTOR AS5004T + TerraMaster D5-300C
The D5-300C does not operate correctly when connected to the ASUSTOR AS5004T.
The DAS contains four drives and is detected by the NAS as four USB mass-storage devices. However, the USB connection is not stable and the DAS eventually loses connectivity.
The important point is that the individual disks themselves are detected correctly when the connection is working.
I performed several checks on the Linux side, including examining /sys/block/, the SCSI devices and the USB device topology.
The D5-300C devices are presented as:
TerraMas TDAS
SCSI Direct-Access
USB Mass Storage
Correct disk capacities are detected
The disks are partitioned and readable
NTFS volumes can be mounted
The system therefore appears to recognize the DAS and its disks correctly at the beginning.
However, the USB connection subsequently drops completely.
The kernel reports events such as:
usb 1-4: USB disconnect
usb 1-4.1: USB disconnect
usb 1-4.2: USB disconnect
usb 1-4.3: USB disconnect
usb 1-4.4: USB disconnect
followed by:
Synchronize Cache(10) failed:
Result: hostbyte=DID_NO_CONNECT driverbyte=DRIVER_OK
This happens for all four disks.
After the disconnect, all four USB devices disappear from the system.
The important observation is that this is not simply a filesystem or partition problem: the entire USB topology of the D5-300C disappears from the NAS.
After reconnecting/reinitializing the DAS, the four disks are detected again and the NTFS volumes can once again be mounted.

2. USB topology
The D5-300C is connected through the ASUSTOR's external PCIe/USB controller.
The Linux device paths show the four disks behind the same USB hub:
.../usb1/1-4/1-4.1/...
.../usb1/1-4/1-4.2/...
.../usb1/1-4/1-4.3/...
.../usb1/1-4/1-4.4/...
This confirms that the four disks are being presented through the D5-300C USB enclosure/hub rather than as independent directly attached SATA devices.
The failure affects the whole USB connection rather than a single disk.

3. D5-300C disk detection
The D5-300C correctly reports disks with different capacities.
For example, the kernel detects:
2 TB disks
3 TB disk
4 TB disk
with the expected logical block counts and 4096-byte physical sectors where applicable.
The kernel also reports:
Write Protect is off
Write cache: enabled
Read cache: enabled
and successfully detects the partitions.
The NTFS filesystem driver (ufsd) is also able to mount the volumes as read/write before the USB connection is lost.
Therefore, the initial disk detection, partition detection and filesystem mounting all work.
The failure occurs later at the USB connectivity level.

4. QNAP TS-231P + TerraMaster D5-300C
I also tested the same D5-300C with a QNAP TS-231P.
The purpose of this test was to determine whether the problem followed the D5-300C or was specific to the NAS/USB implementation.
The result is important:
The D5-300C does not show the same problem when connected to the QNAP TS-231P.
This strongly suggests that the D5-300C itself is not simply defective at the hardware level.

5. TerraMaster D4-320 comparison
I also tested a second TerraMaster DAS, the D4-320, with both NAS systems.
The D4-320 works correctly with:
ASUSTOR AS5004T
QNAP TS-231P
This is another important control test.
The ASUSTOR AS5004T is therefore capable of operating correctly with a TerraMaster USB DAS.
The QNAP TS-231P is also capable of operating correctly with the D5-300C.
The problematic combination is specifically:
ASUSTOR AS5004T + TerraMaster D5-300C
while:
ASUSTOR AS5004T + TerraMaster D4-320 → works correctly
and:
QNAP TS-231P + TerraMaster D5-300C → works correctly

6. Conclusion
Based on these tests, I do not believe this is simply a defective disk or a filesystem problem.
The evidence points toward a USB compatibility/stability issue between the D5-300C and the ASUSTOR AS5004T, potentially related to the USB bridge/hub implementation, USB power management, USB mass-storage/UAS handling, or the D5-300C firmware.
The fact that:
the D5-300C correctly detects all disks;
the partitions are correctly detected;
NTFS volumes can be mounted;
the D5-300C works with the QNAP TS-231P;
the D4-320 works with the ASUSTOR AS5004T;
and the failure causes the entire D5-300C USB topology to disappear;
makes me suspect a compatibility issue rather than a simple hardware failure.
I have also seen reports on this forum of TerraMaster technical support providing firmware updates for specific D5-300C revisions.

Therefore, I would like to ask whether TerraMaster can check the hardware/firmware revision of my D5-300C and confirm whether there is a newer or non-public firmware version that could improve compatibility with the ASUSTOR AS5004T.

If required, I can provide the complete dmesg output, USB topology, device information and any other diagnostic information needed.

Has anyone else experienced the same issue with a D5-300C + ASUSTOR NAS, particularly with the AS5004T?

Thank you.

The ASUSTOR AS5004T has three USB 3.0 ports and two USB 2.0 ports. Have you tested different ports? To control for variables, were the same cables used during testing?

Please execute `lsusb -t` and `lsusb` on the AS5004T and send us the output.