Unable to mount USB Flash memory created on CentOS

James B. Byrne byrnejb at harte-lyne.ca
Fri Jul 28 19:14:27 UTC 2017

On Fri, July 28, 2017 14:51, Polytropon wrote:
> On Fri, 28 Jul 2017 13:22:06 -0400, James B. Byrne via
> freebsd-questions wrote:
>> On my new FreeBSD workstation I am trying to read data off of a USB
>> 'key' flash memory stick recorded using rsync on a CentOS-6 system.
>> I was able to do this successfully up until the point that I inserted
>> another usb stick.  Now I cannot mount or read either.
> Did you unmount the previous stick correctly?


> When you say it was "recorded" with CentOS, which file system
> has been used? Or is it a "raw" file (no file system at all,
> output written directly to the device)?

ext2fs.  I was formerly able to read these usb sticks on the new
FreeBSD based workstation.  The problem only surfaced when I inserted
a second usb flash drive.

>> I probably made things worse by first removing both keys from the
>> host and then deleting the contents of /media.  However, that is
>> done.
> That should not be a big problem, as /media is usually populated
> automatically by a desktop environment's automounter, or manually
> by the system administrator (which implies that you can easily
> recreate required mountpoints under /media if you use /etc/fstab
> as a template).

This is what I have in /etc/fstab

# Device           Mountpoint     FStype        Options        Dump  
/dev/ada0p2.eli    none           swap          sw             0      0
/dev/ada1p2.eli    none           swap          sw             0      0
fdesc              /dev/fd        fdescfs       rw             0      0
proc               /proc          procfs        rw             0      0

>> At the moment what happens is that upon insertion the 'computer'
>> browser pane will display a filesystem labelled 'USB Drive' but I
>> cannot open it for viewing.
> Is it empty? When you say it's being opened, I assume this is a
> file browser - but from which desktop? They are quite different!

I am using the Mate desktop and the file browser application shown as
'Computer' on the desktop.

> Check things easily: Open a terminal and check the outpuf of
> 	% mount -v
# mount -v
zroot/ROOT/default on / (zfs, local, noatime, nfsv4acls, fsid
devfs on /dev (devfs, local, multilabel, fsid 00ff007171000000)
fdescfs on /dev/fd (fdescfs, fsid 01ff005959000000)
procfs on /proc (procfs, local, fsid 02ff000202000000)
zroot/tmp on /tmp (zfs, local, noatime, nosuid, nfsv4acls, fsid
zroot/usr/home on /usr/home (zfs, local, noatime, nfsv4acls, fsid
zroot/usr/ports on /usr/ports (zfs, local, noatime, nosuid, nfsv4acls,
fsid c3353930de6b28f5)
zroot/usr/src on /usr/src (zfs, local, noatime, nfsv4acls, fsid
zroot/var/audit on /var/audit (zfs, local, noatime, noexec, nosuid,
nfsv4acls, fsid 0dde5904de17aec3)
zroot/var/crash on /var/crash (zfs, local, noatime, noexec, nosuid,
nfsv4acls, fsid bd542313de5b6740)
zroot/var/log on /var/log (zfs, local, noatime, noexec, nosuid,
nfsv4acls, fsid cc095ee9de26f4fd)
zroot/var/mail on /var/mail (zfs, local, nfsv4acls, fsid
zroot/var/tmp on /var/tmp (zfs, local, noatime, nosuid, nfsv4acls,
fsid 1c322eeade9a7a06)
zroot on /zroot (zfs, local, noatime, nfsv4acls, fsid 521cbba2def75276)

> Is the USB stick (usually /dev/da0 or /dev/da0s1 or something
> like that) _really_ mounted?

Not that I can see. That appears to be the essence of the problem.

> Check what's on the USB stick, using
> 	% gpart show da0
# gpart show da0
=>       63  122915265  da0  MBR  (59G)
         63       8001       - free -  (3.9M)
       8064  122907264    1  !12  [active]  (59G)

dmesg shows this:

ugen3.2: <Kingston> at usbus3
umass0: <Kingston DataTraveler 2.0, class 0/0, rev 2.00/1.00, addr 2>
on usbus3
umass0:  SCSI over Bulk-Only; quirks = 0x8100
umass0:5:0: Attached to scbus5
da0 at umass-sim0 bus 0 scbus5 target 0 lun 0
da0: <Kingston DataTraveler 2.0 PMAP> Removable Direct Access SPC-2
SCSI device
da0: Serial Number 50E549C20210BF10A9BC4174
da0: 40.000MB/s transfers
da0: 60017MB (122915328 512 byte sectors)
da0: quirks=0x3<NO_SYNC_CACHE,NO_6_BYTE>

>> Neither does a mount command show in the
>> right-click popup menu.
> So it probably _is_ mounted. Does the menu show a "detach",
> "unoumt" or "eject" entry or symbol?


> As I said, don't rely on distracting pictural elements. Query
> the OS directly using the command line. It will tell you what
> is _really_ happening.

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James B. Byrne                mailto:ByrneJB at Harte-Lyne.ca
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