Unable to mount USB Flash memory created on CentOS

[Datasmurf]

On Mon, 31 Jul 2017 11:49:52 -0400
"James B. Byrne via freebsd-questions" <freebsd-questions at freebsd.org>
wrote:

> Lest it be lost in the minutiae of solving this difficulty I thank you
> for all your help.
> 
> 
> On Sat, July 29, 2017 05:01, Polytropon wrote:
> >
> > I'd suggest you use the Linux native fsck (e2fsck). If I
> > remember correctly, there is also an "ext2 fsck" in the
> > port e2fsprogs with the same name.
> >
> > Or maybe it came with FUSE?
> >
> > Basically, you'd so something like
> >
> > 	# fsck -t ext2 /dev/da1
> >
> > or, as I mentioned,
> >
> > 	# e2fsck /dev/da1
> >
> > An automatic file system type detection relies on an entry
> > in /etc/fstab, which you don't have, so you need to specify
> > the FS type manually.
> >
> >
> 
> When I try to verify the flash drives I see this:
> 
> # e2fsck /dev/da1
> e2fsck 1.43.4 (31-Jan-2017)
> ext2fs_open2: Bad magic number in super-block
> e2fsck: Superblock invalid, trying backup blocks...
> e2fsck: Bad magic number in super-block while trying to open /dev/da1
> . . .
> 
> So I redid the command using the partition values instead:
> 
> # e2fsck /dev/da0s1
> e2fsck 1.43.4 (31-Jan-2017)
> CA_HLL_2016_BKUP has gone 267 days without being checked, check
> forced. Pass 1: Checking inodes, blocks, and sizes
> Pass 2: Checking directory structure
> Pass 3: Checking directory connectivity
> Pass 4: Checking reference counts
> Pass 5: Checking group summary information
> Error writing file system info: Invalid argument
> 
> CA_HLL_2016_BKUP: ***** FILE SYSTEM WAS MODIFIED *****
> 
> However, the device remains unmountable in Mate.

You have to be careful and choose the correct superblock.

run e2fsck with -b option as root. I had similar problems with
external HDD's in the past. But using the correct superblock with the
fsck command fixed it. 

e2fsck -b 32768 /dev/da0s1

Reading man e2fsck won't hurt too. 



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