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[Solved] Asuswrt-Merlin USB Mount Issue


New Around Here
This is a bit of an odd one, and I think I've searched pretty thoroughly. Have been using my RT-AC86U with factory asuswrt for a little while, but recently installed Merlin for the ability to run cron jobs. After install, did a factory reset and aside from standard WAN settings left things pretty well at their defaults.

I have a 5TB USB drive plugged into the USB3 port of the router with two partitions. I intend to share one with SMB and use the other for Time Machine. (This problem arises before getting into the Time Machine part.) For what it's worth, the whole setup was working ok before installing Merlin.

Now, it seems the router is unable to mount the second partition. The drive has GPT partition table with two ext4 partitions, the first about 1.4GB and the second about 3GB.

In the web interface, only the first partition is listed when hovering over the green USB icon, or within the SMB configuration list.

By SSH, fdisk shows all partitions:
Disk /dev/sda: 4294967295 sectors, 2047G
Logical sector size: 512
Disk identifier (GUID): 0a53e242-e34a-417e-bac7-f9184e55dcaa
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 9767541133

Number  Start (sector)    End (sector)  Size       Code  Name
   1              40          409639        200M   0700  EFI System Partition
   2          411648      2930098175       1396G   0700  Time Machine
   3      2930098176      9767540735       3260G   0700  Nosflow
But mounting fails:
[email protected]:/tmp/mnt# mkdir sda3
[email protected]:/tmp/mnt# mount /dev/sda3 sda3
mount: mounting /dev/sda3 on sda3 failed: Invalid argument
[email protected]:/tmp/mnt# mount -t ext4 /dev/sda3 sda3
mount: mounting /dev/sda3 on sda3 failed: Invalid argument
I did verify that the disk mounts on another computer without issues.

I understand that sometimes GPT and large disk support can be sketchy, but given that it was working fine on stock asuswrt, I wasn't expecting any problems with Merlin. Is this a known issue, or am I doing something wrong?


Part of the Furniture
Try naming the disk something other than sda3. There could be conflict. (as it can be used by the system, when the volume isn't named). Name it something easy to test first.


New Around Here
Not sure how it happened, but it looks like the journal got corrupted on the ext4 filesystem, and that's why it refused to mount / wasn't recognized. Exploring the system log pointed in the right direction, and re-creating the filesystem from the router fixed things (though apparently the router software has an older version of tune2fs, which was interesting).

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