This article explains why users may be unable to mount the USB device when they want to transfer important files on the NFX platform and why they may run into the "wrong fs type" error.

When trying to mount a USB device, the following error message is seen and the operation fails:

root@jtac-NFX250-S2-r006-host:~# mount /dev/sdb1 /var/usb
mount: /dev/sdb1 is write-protected, mounting read-only
mount: wrong fs type, bad option, bad superblock on /dev/sdb,
       missing codepage or helper program, or other error

In some cases, useful information is found in syslog. Try dmesg | tail or so.

In order to use a USB device to transfer files, the USB needs to be formatted as EXT4 format. You can format the USB device as EXT4 from hypervisor by using the command mkfs.ext4 .

Example

root@jtac-NFX250-S2-r006-host:/var# mkfs.ext4 /dev/sdb1
mke2fs 1.42.9 (28-Dec-2013)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
250976 inodes, 1003264 blocks
50163 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=1027604480
31 block groups
32768 blocks per group, 32768 fragments per group
8096 inodes per group
Superblock backups stored on blocks:
        32768, 98304, 163840, 229376, 294912, 819200, 884736

Allocating group tables: done                            
Writing inode tables: done                            
Creating journal (16384 blocks): done
Writing superblocks and filesystem accounting information: done 

Now that the USB device is formatted as EXT4, you can now mount the USB device.