[NTLUG:Discuss] How does one identify a device based on the kernel designation/number?

[Robert Citek]

On Thu, Apr 24, 2008 at 10:56 AM, Bob Netherton <Bob.Netherton at sun.com> wrote:
>  On Thu, 2008-04-24 at 09:51 -0500, Richard Geoffrion wrote:
>  > Where does one go to track down and identify/interpet  which devices
>  > belongs to a kernel assigned device number??
>  >
>  > kernel:  I/O error: dev 08:60, sector 0
>  > kernel:  I/O error: dev 08:61, sector 0
>  >
>  >
>  > How does one find what device 08:60 is??
>
>  That sure looks like a nice major:minor pair.
>
>  # cat /proc/devices
>  <snip>
>
>  Block devices:
>   1 ramdisk
>   2 fd
>   8 sd
>   9 md
>   11 sr
>
>  which shows that 8 is the sd driver.
>
>  The minor number comes in groups of 8, so 60 and 61 would be
>
>  sde4 and sde5.

I think its groups of 16 for the sd devices (see below), which would
put it at sdc12 and sdc13.

>  Does that sound right to you ?   Check /dev/sd*

To check:

$ ls -l /dev/sd*
brw-rw---- 1 root disk    8,  0 2008-04-16 11:33 /dev/sda
brw-rw---- 1 root disk    8,  1 2008-04-16 11:33 /dev/sda1
brw-rw---- 1 root disk    8,  2 2008-04-16 16:33 /dev/sda2
brw-rw---- 1 root disk    8,  3 2008-04-16 11:33 /dev/sda3
brw-rw---- 1 root disk    8,  5 2008-04-16 11:33 /dev/sda5
brw-rw---- 1 root plugdev 8, 16 2008-04-24 14:17 /dev/sdb
brw-rw---- 1 root plugdev 8, 17 2008-04-24 14:17 /dev/sdb1
brw-rw---- 1 root plugdev 8, 26 2008-04-24 14:17 /dev/sdb10
brw-rw---- 1 root plugdev 8, 27 2008-04-24 14:17 /dev/sdb11
brw-rw---- 1 root plugdev 8, 28 2008-04-24 14:17 /dev/sdb12
brw-rw---- 1 root plugdev 8, 29 2008-04-24 14:17 /dev/sdb13
brw-rw---- 1 root plugdev 8, 30 2008-04-24 14:17 /dev/sdb14
brw-rw---- 1 root plugdev 8, 31 2008-04-24 14:17 /dev/sdb15
brw-rw---- 1 root plugdev 8, 18 2008-04-24 14:17 /dev/sdb2
brw-rw---- 1 root plugdev 8, 19 2008-04-24 14:17 /dev/sdb3
brw-rw---- 1 root plugdev 8, 20 2008-04-24 14:17 /dev/sdb4
brw-rw---- 1 root plugdev 8, 21 2008-04-24 14:17 /dev/sdb5
brw-rw---- 1 root plugdev 8, 22 2008-04-24 14:17 /dev/sdb6
brw-rw---- 1 root plugdev 8, 23 2008-04-24 14:17 /dev/sdb7
brw-rw---- 1 root plugdev 8, 24 2008-04-24 14:17 /dev/sdb8
brw-rw---- 1 root plugdev 8, 25 2008-04-24 14:17 /dev/sdb9

Unfortunately, that doesn't quite match the actual layout of the
drive, which has more partitions:

$ fdisk -l /dev/sdb

Disk /dev/sdb: 160.0 GB, 160041885696 bytes
255 heads, 63 sectors/track, 19457 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x0001a8c9

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1   *           1        2433    19543041    b  W95 FAT32
/dev/sdb2            2434        6257    30716280   83  Linux
/dev/sdb3            6258        6270      104422+   b  W95 FAT32
/dev/sdb4            6271       19457   105924577+   5  Extended
/dev/sdb5            6271       12958    53721328+  83  Linux
/dev/sdb6           12959       14175     9775521   83  Linux
/dev/sdb7           14176       14298      987966   83  Linux
/dev/sdb8           14299       15515     9775521   83  Linux
/dev/sdb9           15516       16732     9775521   83  Linux
/dev/sdb10          16733       17949     9775521   83  Linux
/dev/sdb11          17950       19166     9775521   83  Linux
/dev/sdb12          19167       19179      104391   83  Linux
/dev/sdb13          19180       19192      104391   83  Linux
/dev/sdb14          19193       19205      104391   83  Linux
/dev/sdb15          19206       19218      104391   83  Linux
/dev/sdb16          19219       19231      104391   83  Linux
/dev/sdb17          19232       19244      104391   83  Linux
/dev/sdb18          19245       19257      104391   83  Linux
/dev/sdb19          19258       19270      104391   83  Linux
/dev/sdb20          19271       19283      104391   83  Linux
/dev/sdb21          19284       19296      104391   83  Linux

$ cat /proc/partitions
major minor  #blocks  name

   8     0   78156288 sda
   8     1   20972826 sda1
   8     2   54805747 sda2
   8     3          1 sda3
   8     5    2377588 sda5
   8    16  156290904 sdb
   8    17   19543041 sdb1
   8    18   30716280 sdb2
   8    19     104422 sdb3
   8    20          1 sdb4
   8    21   53721328 sdb5
   8    22    9775521 sdb6
   8    23     987966 sdb7
   8    24    9775521 sdb8
   8    25    9775521 sdb9
   8    26    9775521 sdb10
   8    27    9775521 sdb11
   8    28     104391 sdb12
   8    29     104391 sdb13
   8    30     104391 sdb14
   8    31     104391 sdb15

Regards,
- Robert