on boot, access beyond end of device

[Phil Meyer]

Todd Denniston wrote:
> 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.
>

Yes, but the df output should not be LARGER than the /proc/partitions 
number.  It seems reasonable that it could/should be smaller.

So my wording of identifying a mismatch was poor.  Perhaps it should be 
said that the df number if larger than the /proc/partitions number 
indicates this type of problem.

Sorry for the confusion.  It was clear in my head when I wrote it, can't 
you read my mind? :)