special device does not exist

[T o n g <mlist4suntong@yahoo.com>]

Hi, 

I'm having a very weird problem. 

 % mount /dev/sdb7 /mnt/tmp
 mount: special device /dev/sdb7 does not exist

I.e., my sdb7 is not in my system's device list. But the partition does 
exist:

 $ fdisk -l /dev/sdb | grep sdb7
 /dev/sdb7           15300       17848    20474842   83  Linux

And this is from 'cfdisk /dev/sdb'

 Name  Flags Part Type  FS Type     [Label]  Size (MB)
 -----------------------------------------------------
 . . . 
 sdb7  NC     Logical   Linux                 20966.24
 sdb8  NC     Logical   Linux ext3  [os21]     6292.34
 sdb9  NC     Logical   Linux ext3  [os22]     6292.34
 . . . 

Actually, it is not only sdb7 that is missing from my system's device 
list but many others as well, including sdb8 & sdb9, which all show fine 
in fdisk, sfdisk, or cfdisk. Just that they are not there:

$ ls -l /dev/sdb?
brw-rw---- 1 root disk 8, 17 2011-11-05 14:10 /dev/sdb1
brw-rw---- 1 root disk 8, 18 2011-11-05 14:10 /dev/sdb2
brw-rw---- 1 root disk 8, 21 2011-11-05 14:10 /dev/sdb5
brw-rw---- 1 root disk 8, 22 2011-11-05 14:10 /dev/sdb6

This is after I'll issued the 'udevadm trigger' for udev to update my 
system's device list.

I've tried to recreate the device myself:

 mknod -m 660 /dev/sdb7 b 8 23

$ ls -l /dev/sdb*
brw-rw---- 1 root disk 8, 16 2011-11-05 14:10 /dev/sdb
brw-rw---- 1 root disk 8, 17 2011-11-05 14:10 /dev/sdb1
brw-rw---- 1 root disk 8, 27 2011-11-05 14:10 /dev/sdb11
brw-rw---- 1 root disk 8, 29 2011-11-05 14:10 /dev/sdb13
brw-rw---- 1 root disk 8, 30 2011-11-05 14:10 /dev/sdb14
brw-rw---- 1 root disk 8, 31 2011-11-05 14:10 /dev/sdb15
brw-rw---- 1 root disk 8, 18 2011-11-05 14:10 /dev/sdb2
brw-rw---- 1 root disk 8, 21 2011-11-05 14:10 /dev/sdb5
brw-rw---- 1 root disk 8, 22 2011-11-05 14:10 /dev/sdb6
brw-r--r-- 1 root root 8, 23 2011-11-05 14:14 /dev/sdb7

But somehow it is not working:

% mkfs.ext3 -v /dev/sdb7
mke2fs 1.41.12 (17-May-2010)
mkfs.ext3: No such device or address while trying to determine filesystem 
size

Please help. 

Thanks

-- 
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