[gentoo-user] Balky mounting of external devices

[gentoo-user] Balky mounting of external devices

[Walter Dnes]

  This has happened to me with a few different external devices (USB
keys, etc) on multiple computers, so it seems to be a generic problem.
Right now, I have an HTC Desire HD with the smae problem...

* Either hit {CTRL}{ALT}{F12} to switch to tty12 or else (as root) execute
  "tail -f /var/log/messages"

* Attach a device to the PC's USB port, and you'll see a bunch of stuff
  spewing out.  In my case, the last 3 lines are...

Oct  7 20:50:23 localhost kernel: [114416.426175] scsi 26:0:0:0: Direct-Access     HTC      Android Phone    0100 PQ: 0 ANSI: 2
Oct  7 20:50:23 localhost kernel: [114416.426336] sd 26:0:0:0: Attached scsi generic sg3 type 0
Oct  7 20:50:23 localhost kernel: [114416.432119] sd 26:0:0:0: [sdc] Attached SCSI removable disk

* If I try mounting /dev/sdc1 (either as ordinary user or root), it's
  not found
* "fdisk -l" doesn't even see /dev/sdc

***BUT***

* as root "fdisk /dev/sdc", and quit immediately

and now "fdisk -l" sees /dev/sdc, and regular user can mount it.  Has
anyone seen this before... and more importantly, found a solution?

-- 
Walter Dnes <waltdnes@waltdnes.org>

Re: [gentoo-user] Balky mounting of external devices

[Neil Bothwick]

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On Fri, 21 Oct 2011 20:03:21 -0400, Walter Dnes wrote:

> * Attach a device to the PC's USB port, and you'll see a bunch of stuff
>   spewing out.  In my case, the last 3 lines are...
> 
> Oct  7 20:50:23 localhost kernel: [114416.426175] scsi 26:0:0:0:
> Direct-Access     HTC      Android Phone    0100 PQ: 0 ANSI: 2 Oct  7
> 20:50:23 localhost kernel: [114416.426336] sd 26:0:0:0: Attached scsi
> generic sg3 type 0 Oct  7 20:50:23 localhost kernel: [114416.432119] sd
> 26:0:0:0: [sdc] Attached SCSI removable disk
> 
> * If I try mounting /dev/sdc1 (either as ordinary user or root), it's
>   not found
> * "fdisk -l" doesn't even see /dev/sdc

This came up recently with a different subject. Your device does not have
a partition table, instead the filesystem occupies the whole device
(sometimes referred to as a "superfloppy" format). There's nothing wrong
with this, I have a couple of USB sticks like it, and my Nexus S is the
same.

Your automounter should still pick it up.


-- 
Neil Bothwick

Top Oxymorons Number 33: American history

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[gentoo-user] [SOLVED] Balky mounting of external devices

[Walter Dnes]

On Sat, Oct 22, 2011 at 09:21:50PM +0100, Neil Bothwick wrote

> This came up recently with a different subject. Your device does not have
> a partition table, instead the filesystem occupies the whole device
> (sometimes referred to as a "superfloppy" format). There's nothing wrong
> with this, I have a couple of USB sticks like it, and my Nexus S is the
> same.
> 
> Your automounter should still pick it up.

  I don't use an automounter.  I like to be in control of what gets
mounted when.  Thanks for the explanation.  With it in mind I've finally
come up with a plan that works.  In /etc/sudoers.d/001 I've included...

waltdnes    i3 = (root) NOPASSWD: /sbin/fdisk -l /dev/sdc

  And there's an entry for a vfat device in /etc/fstab for directory
/mnt/extc.  The command "/sbin/fdisk -l /dev/sdc" seems to read in the
partition table into the system and things work from there on in.  fdisk
only works as root, hence the sudo command.  Here's a sample session...

===================================================================
waltdnes@i3 ~ $ mount /mnt/extc        
mount: special device /dev/sdc1 does not exist
waltdnes@i3 ~ $ sudo /sbin/fdisk -l /dev/sdc

Disk /dev/sdc: 16.0 GB, 16012804096 bytes
256 heads, 63 sectors/track, 1939 cylinders, total 31275008 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

   Device Boot      Start         End      Blocks   Id  System
/dev/sdc1   *        2048    31275007    15636480    c  W95 FAT32 (LBA)
waltdnes@i3 ~ $ mount /mnt/extc
waltdnes@i3 ~ $
===================================================================

  The mount after "sudo /sbin/fdisk -l /dev/sdc" is successful.  So all
I need is a short script "~/bin/mntc" like so...

#!/bin/bash
sudo /sbin/fdisk -l /dev/sdc
mount /mnt/extc

-- 
Walter Dnes <waltdnes@waltdnes.org>

Re: [gentoo-user] [SOLVED] Balky mounting of external devices

[Neil Bothwick]

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On Sat, 22 Oct 2011 23:38:45 -0400, Walter Dnes wrote:

> On Sat, Oct 22, 2011 at 09:21:50PM +0100, Neil Bothwick wrote
> 
> > This came up recently with a different subject. Your device does not
> > have a partition table, instead the filesystem occupies the whole
> > device (sometimes referred to as a "superfloppy" format). There's
> > nothing wrong with this, I have a couple of USB sticks like it, and
> > my Nexus S is the same.
> > 
> > Your automounter should still pick it up.
> 
>   I don't use an automounter.  I like to be in control of what gets
> mounted when.

Then use an intelligent automounter, that only mounts things you want it
to and lets you make choices about the rest :)

> Thanks for the explanation. With it in mind I've finally 
> come up with a plan that works.
> In /etc/sudoers.d/001 I've included...
> 
> waltdnes    i3 = (root) NOPASSWD: /sbin/fdisk -l /dev/sdc
> 
>   And there's an entry for a vfat device in /etc/fstab for directory
> /mnt/extc.  The command "/sbin/fdisk -l /dev/sdc" seems to read in the
> partition table into the system and things work from there on in.  fdisk
> only works as root, hence the sudo command.  Here's a sample session...
> 
> ===================================================================
> waltdnes@i3 ~ $ mount /mnt/extc        
> mount: special device /dev/sdc1 does not exist
> waltdnes@i3 ~ $ sudo /sbin/fdisk -l /dev/sdc
> 
> Disk /dev/sdc: 16.0 GB, 16012804096 bytes
> 256 heads, 63 sectors/track, 1939 cylinders, total 31275008 sectors
> Units = sectors of 1 * 512 = 512 bytes
> Sector size (logical/physical): 512 bytes / 512 bytes
> I/O size (minimum/optimal): 512 bytes / 512 bytes
> Disk identifier: 0x00000000
> 
>    Device Boot      Start         End      Blocks   Id  System
> /dev/sdc1   *        2048    31275007    15636480    c  W95 FAT32 (LBA)
> waltdnes@i3 ~ $ mount /mnt/extc
> waltdnes@i3 ~ $
> ===================================================================

In that case, you have a different situation since there is clearly a
partition on the disk. The partition table may be slightly faulty, hence
the need for fdisk. Recreating the partition table with fdisk should fix
that permanently.


-- 
Neil Bothwick

Those who live by the sword get shot by those who don't.

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Re: [gentoo-user] [SOLVED] Balky mounting of external devices

[Walter Dnes]

On Sun, Oct 23, 2011 at 12:07:23PM +0100, Neil Bothwick wrote

> In that case, you have a different situation since there is clearly a
> partition on the disk. The partition table may be slightly faulty, hence
> the need for fdisk. Recreating the partition table with fdisk should fix
> that permanently.

  I thought about this, and decided not to.  This is how the phone set
up the mini-SD card.  If I change things, then I don't know how the
phone would react.  The main concern is that it work properly in the
phone.  I can work around its idiosyncrasies in linux whenever I need to
transfer photos off the phone, or other stuff to the phone.

-- 
Walter Dnes <waltdnes@waltdnes.org>