[Help] TerraMaster F4-424 Pro – TOS 7 Upgrade: RAID Healthy but All Volumes Show “Volume Corrupted” / 0 B

[Abkbo]

Hi everyone,

I’m looking for some help recovering access to my existing volumes after upgrading my TerraMaster F4-424 Pro from TOS 6 to TOS 7.

I have been searching the web and reading other forum posts about similar TOS/RAID issues. Based on what I have found, I think I understand what happened, but I may be wrong about some of the technical details. I’ll explain the sequence below as clearly as possible.

My NAS has:

- 4 × 4 TB HDDs – "sda", "sdb", "sdc", "sdd"
- HDDs configured as a TRAID storage pool
- 2 × 250 GB NVMe SSDs – "sdza", "sdzb"
- Originally running TOS 6
- My data is on the HDD storage pool

Everything was working normally before I started the TOS 7 upgrade.

What happened

I powered down the NAS and physically disconnected/unseated all four HDDs because I wanted to upgrade only the NVMe/system side first.

With only the NVMe drives connected, I manually upgraded the NAS to an early TOS 7 release (7.0.0747) and then to release (7.0.1140).

Afterwards, I powered down the NAS, pushed the four HDDs back into their bays, and restarted it.

This is where the problem started.

From what I understand after reading other posts and searching online, I think the motherboard gave priority to the SATA HDDs during boot. Since the HDDs still contained the old TOS 6 system information, the NAS booted back into the TOS 6 environment instead of TOS 7.

My assumption is that TOS 6 then detected conflicting/newer TOS 7 system information on the NVMe drives. At that point, TOS reported the HDD RAID/storage pool as corrupted or locked and most storage-management options became unavailable.

Again, this is my understanding of what probably happened rather than something I can confirm with certainty.

What I did to recover the TOS 6 storage pool

While back in TOS 6, I used Disk Manager → Wipe Disk to wipe both NVMe SSDs.

After restarting the NAS, the HDD storage pool came back online.

The RAID then completed a full background synchronization, after which everything returned to a normal/green state.

At this point, the HDD RAID and volumes appeared to be working normally again under TOS 6.

Preparing properly for TOS 7

Before trying the upgrade again, I used the official System Disk Migration tool from inside TOS 6.

The migration completed successfully and moved the System Disk role/tags away from the HDDs and onto NVMe Disk 1.

I also changed the App Center default storage location from the HDD-based Volume 1 to the newly created NVMe Volume 6.

My intention was to make the NVMe drives the system/app storage and leave the four HDDs primarily for my existing data.

Second TOS 7 upgrade

I then:

1. Powered down the NAS.
2. Pulled all four HDDs halfway out of their bays so they were physically disconnected from the SATA backplane.
3. Left only the NVMe SSDs connected.
4. Powered the NAS back on.
5. Confirmed it booted from the NVMe system environment.
6. Manually upgraded to TOS 7.0.1140.
7. Waited for the new TOS 7 desktop/interface to fully load and stabilize.
8. Hot-plugged the four 4 TB HDDs back into their original slots, one at a time.

Current situation

This is where I am stuck.

At the physical disk level, everything appears healthy.

TOS 7 detects all six drives and the Disk page reports them as healthy.

The TerraMaster diagnostic "disk.txt" file also appears to show that the underlying RAID 5 members:

"/dev/sda4"
"/dev/sdb4"
"/dev/sdc4"
"/dev/sdd4"

are assembled and healthy.

The RAID reports a clean state and an AAAA status map, which as far as I understand means all four RAID members are active.

SSH also appears to show that the underlying LVM structure still exists. I can see logical volumes mapped as:

"/dev/vg0/lv0"
"/dev/vg0/lv1"
"/dev/vg0/lv2"
"/dev/vg0/lv3"
"/dev/vg0/lv4"

So, from what I can tell, the physical disks, RAID array, and LVM structures still seem to exist.

However, inside the TOS 7 Volume Manager, I now see:

- Volume 1 – Volume corrupted – "0.00 B / 0 B"
- Volume 2 – Volume corrupted – "0.00 B / 0 B"
- Volume 3 – Volume corrupted – "0.00 B / 0 B"
- Volume 4 – Volume corrupted – "0.00 B / 0 B"
- Volume 5 – Volume corrupted – "0.00 B / 0 B"

All five volumes are locked/red.

SSH limitation

I tried investigating through SSH, but normal administrative SSH access appears to be restricted/sandboxed.

Commands that would normally require root-level access to LVM, mounting, or system mount points fail with Permission denied, so I have avoided trying anything aggressive that might alter the RAID/LVM metadata.

What I need help with

My main concern is recovering the existing volumes without destroying or recreating the RAID/storage pool.

Since the underlying RAID appears healthy and the logical volumes still seem to exist, I am wondering whether this is actually a TOS 7 volume/filesystem recognition or mounting issue, rather than real RAID corruption.

Could someone familiar with TerraMaster/TOS/Linux storage please advise:

- Does the RAID/LVM information above suggest that my data and filesystems are probably still intact?
- Why would TOS 7 detect the RAID and LVM devices correctly but show every volume as 0 B / Volume corrupted?
- Is there a safe way to determine the filesystem type and filesystem health of "/dev/vg0/lv0" through "/dev/vg0/lv4" without modifying anything?
- Could this be caused by TOS 6 → TOS 7 metadata/configuration incompatibility rather than actual filesystem corruption?
- Is there a safe way to make TOS 7 re-import/re-recognize the existing volumes?
- Most importantly, what should I NOT do at this stage to avoid accidentally destroying the existing data?

I have diagnostic files available, which includes "disk.txt", and can provide relevant SSH outputs/screenshots if someone can tell me exactly what information would be useful.

For now, I have not formatted, recreated, initialized, or deleted the HDD storage pool or volumes, because the RAID itself appears to still be healthy.

Any guidance on the safest next step would be greatly appreciated.

[EriChan]

To better assist you in restoring access to your existing volume, please navigate to TOS > Support and Help > Report Issues to generate and download the system report, then send it to our technical support email address at support(at)terra-master.com, and be sure to include the forum link and your forum ID along with it.

If the system report cannot be sent normally, please upload it to a cloud storage service first and then send us the sharing link in your email.