on boot, access beyond end of device

[Todd Denniston]

Mike -- EMAIL IGNORED wrote, On 02/25/2008 06:56 PM:
> On Mon, 25 Feb 2008 22:45:23 +0000, Mike -- EMAIL IGNORED wrote:
> 
>> On Mon, 25 Feb 2008 15:07:20 -0700, Phil Meyer wrote:
>>
>> [...]
>>> compare the numbers between:
>>>
>>> # cat /proc/partitions
>>>
>>> and the first column of:
>>>
>>> # df
>>>
>>> What might have happened long long ago and far far away, is that fdisk
>>> incorrectly calculated the partition size.  It has been known to do
>>> that.
>>>
>>> Allot of the brand new Nokia N810s are shipping with this problem, due
>>> to the manufacturer copying the disk image of a slightly different
>>> model disk to the current one.
>>>
>>> If the partition sizes between those two commands do not match, then
>>> you are at a trouble spot.  You should not add any more data to that
>>> drive. The symptoms described match exactly the symptoms of filling up
>>> a drive with invalid partition sizes.  It can work for years, as long
>>> as you don't go above a certain percentage used, depending upon the
>>> size of the error.
>>>
>>> I would recommend, if they do not match, that you backup, wipe,
>>> repartition, mkfs, boot from rescue and check again, and if ok restore.
>> Indeed they do not match.  I'll take the opportunity to upgrade to FC8.
>>
>> Thanks,
>> Mike.
> 
> I just looked at one of my other boxes, an FC7, which appears to have a
> similar mismatch, but I have not had a problem with it (yet).
> 
> [root at mbrc32 ~]# cat /proc/partitions
> major minor  #blocks  name
> 
>    8     0   78150744 sda
>    8     1     104391 sda1
>    8     2   78043770 sda2
>  253     0   75956224 dm-0
>  253     1    2031616 dm-1
> 
> 
> [root at mbrc32 ~]# df
> Filesystem           1K-blocks      Used Available Use% Mounted on
> /dev/mapper/VolGroup00-LogVol00
>                       73575592  14177456  55600328  21% /
> /dev/sda1               101086     18584     77283  20% /boot
> tmpfs                   517536         4    517532   1% /dev/shm
> 
> 

Assumption: A) 4K inodes in the file system,
B) /dev/mapper/VolGroup00-LogVol00 is on dm-0 only.
C) /proc/partitions is the correct thing to be comparing against.

try confirming:
tune2fs -l /dev/mapper/VolGroup00-LogVol00 |grep "Block count:"
is equal to
75956224/4 = 18989056

to be sure of the method look at
tune2fs -l /dev/sda1|grep "Block count:"
compared with:
104391/4 = 26097

IIRC "Block count:" from tune2fs is how big the file system things the hard 
drive/volume group is.  IIRC the df data is skewed by the  "Reserved block 
count" and possibly the Journal size.

-- 
Todd Denniston
Crane Division, Naval Surface Warfare Center (NSWC Crane)
Harnessing the Power of Technology for the Warfighter