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ext4 USB 3.0 drive failing to mount - unsupported optional features

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drummer914

Occasional Visitor
I'm trying to get a 32GB flash drive to mount on my RT-AC68P. I used the latest version of gparted to format it to ext4 and everything seemed fine. Here are the logs from the router. Running 380.65_2. Any ideas?

Code:
Mar 16 11:24:13 kernel: usb 1-1: new high speed USB device using ehci_hcd and address 4
Mar 16 11:24:13 kernel: scsi2 : usb-storage 1-1:1.0
Mar 16 11:24:14 kernel: scsi 2:0:0:0: Direct-Access     SanDisk  Ultra Fit        1.00 PQ: 0 ANSI: 6
Mar 16 11:24:14 kernel: sd 2:0:0:0: Attached scsi generic sg0 type 0
Mar 16 11:24:14 kernel: sd 2:0:0:0: [sda] 60062500 512-byte logical blocks: (30.7 GB/28.6 GiB)
Mar 16 11:24:14 kernel: sd 2:0:0:0: [sda] Write Protect is off
Mar 16 11:24:14 kernel: sd 2:0:0:0: [sda] Assuming drive cache: write through
Mar 16 11:24:14 kernel: sd 2:0:0:0: [sda] Assuming drive cache: write through
Mar 16 11:24:14 kernel:  sda: sda1
Mar 16 11:24:14 kernel: sd 2:0:0:0: [sda] Assuming drive cache: write through
Mar 16 11:24:14 kernel: sd 2:0:0:0: [sda] Attached SCSI removable disk
Mar 16 11:24:14 kernel: EXT4-fs (sda1): couldn't mount RDWR because of unsupported optional features (400)
Mar 16 11:24:14 kernel: EXT3-fs (sda1): error: couldn't mount because of unsupported optional features (240)
Mar 16 11:24:14 kernel: EXT2-fs (sda1): error: couldn't mount because of unsupported optional features (240)
Mar 16 11:24:14 hotplug[2537]: USB /dev/sda1(ext) failed to mount at the first try!
Mar 16 11:24:14 usb: USB /dev/sda1(ext) failed to mount at the first try!
Mar 16 11:24:14 kernel: EXT3-fs (sda1): error: couldn't mount because of unsupported optional features (240)
Mar 16 11:24:14 kernel: EXT4-fs (sda1): couldn't mount RDWR because of unsupported optional features (400)
Mar 16 11:24:14 kernel: EXT2-fs (sda1): error: couldn't mount because of unsupported optional features (240)
 
Last edited:
What format did you select? Cifs, ntfs,...?

I used ntfs 4K sectors on my usb3 drive and that works well.


Sent from my iPhone using Tapatalk
 
I'd like to see if I can get ext4 working. I'm sure it's ext4 that is the problem though (it's mentioned in the title, just not in the body of my post - I'll edit)
 
I would try quick formatting it ntfs on a windows box and try again. Routers will be limited as appliances.


Sent from my iPhone using Tapatalk
 
I'm using ext4 without any problems as well. I'd suggest that you build the file system again, but this time use mkfs.ext4 on the router itself. That way it shouldn't be adding any features it doesn't know about.
 
FWIW - ran into a similar problem with Lexar USB3 drives - and it was the factory partition map...

fdisk on debian wouldn't deal with it correctly, ended up using GNU parted, and nuking every partition on the device and starting over...

Don't feel bad - Solaris used to barf on 520K sectors, which is common on fibre-channel arrays, and the drives are cheap - and they wouldn't format correctly, as Solaris usually likes 512K sectors - one would have to use the scu package to force the issue...
 
I run AC-68U, which seems almost similar to those of OP.
Apologies, you need to specify the full path:

Code:
admin@RT-AC68U:/# /usr/sbin/mkfs.ext4
Usage: mkfs.ext4 [-c|-l filename] [-b block-size] [-C cluster-size]
        [-i bytes-per-inode] [-I inode-size] [-J journal-options]
        [-G flex-group-size] [-N number-of-inodes]
        [-m reserved-blocks-percentage] [-o creator-os]
        [-g blocks-per-group] [-L volume-label] [-M last-mounted-directory]
        [-O feature[,...]] [-r fs-revision] [-E extended-option[,...]]
        [-t fs-type] [-T usage-type ] [-U UUID] [-jnqvDFKSV] device [blocks-count]
 
Bummer! Only these FS commands are listed in my /usr/sbin dir:
That's very strange. I've just checked the latest RT-AC68U firmwares from Merlin and John and they both have those files as symbolic links.:confused:

Code:
-rwxr-xr-x    1 admin    root         85448 Jun 27 14:31 mke2fs
lrwxrwxrwx    1 admin    root             6 Jun 27 14:31 mkfs.ext2 -> mke2fs
lrwxrwxrwx    1 admin    root             6 Jun 27 14:31 mkfs.ext3 -> mke2fs
lrwxrwxrwx    1 admin    root             6 Jun 27 14:31 mkfs.ext4 -> mke2fs
 
Ah. Well this is the Merlin forum so... :rolleyes:

Just thought they are compatible in that way :)
Well, I formatted disk via gparted, but now the router sees and mounts only NTFS partition (SYSTEM), whilst EXT4 is not shown. This is what df -h gives

Code:
Filesystem                Size      Used Available Use% Mounted on
/dev/root                37.4M     37.4M         0 100% /
devtmpfs                124.8M         0    124.8M   0% /dev
tmpfs                   124.9M      1.1M    123.7M   1% /tmp
/dev/mtdblock4           62.8M      3.2M     59.6M   5% /jffs
/dev/sda1               406.3G     18.5G    387.8G   5% /tmp/mnt/SYSTEM

When I try to mount EXT4-partition manually like mount /dev/sda2 /mnt/DATA, it gives me
Code:
mount: mounting /dev/sda2 on /mnt/DATA failed: Invalid argument
Is there any trick?

fdisk -l shows this

Code:
Disk /dev/sda: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks  Id System
/dev/sda1   *           1       53033   425986048   7 HPFS/NTFS
/dev/sda2           53033      121602   550774784  83 Linux
 
Ok, problem solved. I had the same issue as OP:) It seems, that third-party EXT4 format tools are still not compatible with AsusWRT.
 
Ok, problem solved. I had the same issue as OP:) It seems, that third-party EXT4 format tools are still not compatible with AsusWRT.
OK. Thanks for the update.

How did you get around it. Did you just reformat sda2 using another tool or did you have to rebuild the partition table (as MBR instead of GPT)?
 
OK. Thanks for the update.

How did you get around it. Did you just reformat sda2 using another tool or did you have to rebuild the partition table (as MBR instead of GPT)?

For now I reformatted it to EXT3, until I flash Merlin. I found that mkfs.ext3 tool exists on router. However, I am not sure flashing Merlin will bring me mkfs.ext4 formatter. For example, this guide states, that mkfs.ext4 is shipped only with ARM-routers and Merlin sticks to official builds mostly. Anyway, some clarification is highly appreciated: does all OEM builds lack mkfs.ext4 tool and it is added only in custom builds or things go other way?
 

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