Re: rfc: test whether a device has a partition table

[Douglas Gilbert]

viro@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx wrote:
> On Thu, Sep 25, 2003 at 10:42:44AM +1000, Douglas Gilbert wrote:
>
> > I have a USB 500 MB USB key that confuses linux (both 2.4 and
> > 2.6) since it has no partition table. It shows up on my laptop as:
>
>
> Confuses it in which sense?

Al,
Under lk 2.4 (rh9) this is in my log:

Sep 25 10:37:53 localhost kernel: SCSI device sda: 1024000 512-byte hdwr 
sectors (524 MB)
Sep 25 10:37:53 localhost kernel: sda: Write Protect is off
Sep 25 10:37:53 localhost kernel:  sda: sda1 sda2 sda3 sda4

Attached is sector 0 of the device and the output of
"fdisk -l".

lk 2.6.0-test5-bk10 also thinks the device has 4 malformed
partitions.

> > $ cat /proc/scsi/scsi
> > Attached devices:
> > Host: scsi0 Channel: 00 Id: 00 Lun: 00
> >  Vendor: Prolific Model: USBFlashDisk     Rev: 1.00
> >  Type:   Direct-Access                    ANSI SCSI revision: 02
> >
> > I can mount it with:
> > $ mount /dev/sda /mnt/extra
>
>
> So it works fine.  what's the problem?

It is non obvious. W2K and XP handled the USB key without
a problem. An organisation bought a bunch of these USB
"floppies" and expected them to work with linux (like
other USB mass storage devices they had experienced). I
was given one to find out what was wrong ...


BTW Another interesting aspect of this USB key is that
some sectors read before they are ever written can give
a "medium error, unrecoverable read". Once the sector
is written the problem goes away. This shouldn't be a
problem in normal use. [I guess at least sector 0 is
written in the factory :-) ]

Doug Gilbert

Attachment: prolific_sect0.img.gz
Description: GNU Zip compressed data

Disk /dev/sda: 524 MB, 524288000 bytes
17 heads, 59 sectors/track, 1020 cylinders
Units = cylinders of 1003 * 512 = 513536 bytes

   Device Boot    Start       End    Blocks   Id  System
/dev/sda1   ?   1914209   2457017 272218546+  20  Unknown
Partition 1 has different physical/logical beginnings (non-Linux?):
     phys=(356, 97, 46) logical=(1914208, 5, 40)
Partition 1 has different physical/logical endings:
     phys=(357, 116, 40) logical=(2457016, 16, 59)
Partition 1 does not end on cylinder boundary.
/dev/sda2   ?   1326206   1863570 269488144   6b  Unknown
Partition 2 has different physical/logical beginnings (non-Linux?):
     phys=(288, 110, 57) logical=(1326205, 9, 57)
Partition 2 has different physical/logical endings:
     phys=(269, 101, 57) logical=(1863569, 13, 16)
Partition 2 does not end on cylinder boundary.
/dev/sda3   ?    537378   1931558 699181456   53  OnTrack DM6 Aux3
Partition 3 has different physical/logical beginnings (non-Linux?):
     phys=(345, 32, 19) logical=(537377, 4, 25)
Partition 3 has different physical/logical endings:
     phys=(324, 77, 19) logical=(1931557, 10, 42)
Partition 3 does not end on cylinder boundary.
/dev/sda4   *   1390457   1390478     10668+  49  Unknown
Partition 4 has different physical/logical beginnings (non-Linux?):
     phys=(87, 1, 0) logical=(1390456, 5, 1)
Partition 4 has different physical/logical endings:
     phys=(335, 78, 2) logical=(1390477, 9, 38)
Partition 4 does not end on cylinder boundary.

Partition table entries are not in disk order