[ILUG] USB mass storage woes

[Paul Elliott]

Marek McGann m.mcgann at sussex.ac.uk writes: (ILUG)


>Picked up a nice new Philips "wearable audio" mp3 key, but having a
>nightmare trying to mount it under Mandrake 10.0.
>
>mount /dev/sda1 /mnt/usb
>
>either hangs (there's no output and the process can't be killed) or
>reports that /dev/sda1 is not a valid block device. The actual device is
>there though, and in HardDrake's hardware listing is classed as a
>hard-drive. Trying to configure it from there though, just ends up me
>being given my hda partition table with no other devices to choose from.
>
>The output of dmesg is below (the usb mass storage bit is right at the
>end). I'm a desktop user only though, so I'm afraid I have no real idea
>what that all means.
>
>Googling suggests others have similar problems...
>
>Any suggestions?
>
>Marek.

I am not subscribed to Ilug Please CC any replys to me.

I have had similar problems with my 64K philips. Your message 
suggests a partial solution.

I have not found a way around the requirement that you use format
with their software under WINBLOWS. (Maybe you will.) However this only
has to be done once.

The problem is that (depending on how you look at it) is that the
device lies about its size, or that there are several blocks toward
the end of the device that are not readable or writable.  The manual
says as much.  When linux tries to read those blocks, it hangs.

On my SuSE 9.1 system, the hang the USB port occurs when the device is
inserted on hotplugging, even before I try to mount it. The fact that
on your mandrake 10 system it had not hung immeadiately was the clue I
needed.

I tried systems trying to find one that does not hang the usb port
when the device is inserted. (You know it is not hung after insertion
when cat /proc/partitons shows the partition as well as the device.
i.e. both sdc and sdc1. SuSE 8.2 rescue CD fits the bill.

So, I look at /var/log/messages from my 9.1 hang and see the following:

>Aug 17 14:03:13 hrnowl kernel:  sdc:end_request: I/O error, dev sdc, sector 126912
This tells me that 512 byte sector 126912 is the last sector not
readable.

So I boot SuSE 8.2 rescue system. Log on as root.

#mount data disk
mount /dev/sda3 /mnt
cd /mnt/tmp

cat /proc/partitons
#insert the mp3 player HERE!
cat /proc/partitons

#the new device, in my case /dev/sdc is the mp3 player.

#I can not mount /dev/sdc1, because if I do the system will
#try to read the unreadable blocks and the usb port will hang!


#So instead, read all the readable blocks, then use loop back!

#dd if=/dev/sdc bs=512 count=126912 of=part.img #126912 comes from above.

Now with this info saved, I can reboot my regular 9.1 system.

#cd /tmp
#            #I want to fill the blocks that I could not read with zeros!
#cat part.img /dev/zero | dd bs=1M count=64 of=disk.img #this will create
#                                                       #an image that is
#                                                       #at least the right size!

#losetup /dev/loop0 disk.img             #view this image as a major device
                                         #looped back

#fdisk -l -u /dev/loop0

Disk /dev/loop0: 67 MB, 67108864 bytes
8 heads, 32 sectors/track, 512 cylinders, total 131072 sectors
Units = sectors of 1 * 512 = 512 bytes

      Device Boot      Start         End      Blocks   Id  System
/dev/loop0p1   *          55      123903       61924+   1  FAT12
Partition 1 has different physical/logical endings:
     phys=(499, 7, 32) logical=(483, 7, 32)


This tells me sector size=512, fist and only partiotions starts at
sector=55. 512x55=28160 is offset to first partiton. So...


#losetup -o 28160 /dev/loop1 disk.img
#mount /dev/loop1 /mnt

I can now add and delete .mp3 files to /mnt. Remember to leave other
files alone, like settings! After I am done:

#umount /mnt


Now I can reboot SuSE 8.2 rescue and copy the disk image back to
the MP3 player!

#dd bs=512 count=126912 if=/mnt/tmp/disk.img of=/dev/sdc

But this hangs! ^C shows it failed to write sector 123016!
Aparently some of the sectors that were readable were not writable!

No Matter! I take out my MP3 player, and all my songs play fine!


SuSE and other distros should make hotplugging more flexible so that
you can plug one of these wierd devices in without hanging the USB
port! Or at least some kind of option to tell it not to probe!
Then you could do all the above without rebooting!

Coments?

-- 
Paul Elliott                       1(512)837-1096
pelliott at io.com                    PMB 181, 11900 Metric Blvd Suite J
http://www.io.com/~pelliott/pme/   Austin TX 78758-3117
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