Couldn't mount RDWR because of unsupported optional features (400)

[Qmann]

Using an EXT4 USB disk that was created with Ubuntu. I plugged into an older TS569L NAS which gives this error. I need to move a large amount of data from this disk to the TS569L and thought plugging in USB would be quick. I never had any compatibility problems with EXT4, ever,,, so this is new.

The ext4 feature (400) is the new metadata_csum feature. If this feature is enabled and old tools are used to mount the filesystem they will only be able to mount read-only.
https://ext4.wiki.kernel.org/index.php/ ... _Checksums

There are two options:

To create a ext4 filesystem without this feature:
sudo mke2fs /dev/sdb1 -O ^metadata_csum

Or turn it off on an already created filesystem:
sudo tune2fs -O ^metadata_csum /dev/sdb1

My question is if there is any way to enable this by default on TS569L so I don't have this issue going forward? I plan to use this old NAS for backups and would be nice if I can figure this out. I did notice that mkfs.ext4 wasn't installed on the device, so I installed it via Entware but still cannot mount the disk and get the same error.

-Q

[Qmann]

As it turns out, I removed the conflicting feature, and then I was able to mount at least read-only. This might help someone else so worth posting IMHO.

Code: Select all

tune2fs -l /dev/sde1 | grep features [show features]

sudo tune2fs -O ^uninit_bg /dev/sde1  [remove feature]

mount -o ro,noload -t ext4 /dev/sde1 /mnt/test  [mount read only]