Blew away my partition table

J. Epperson Dell at epperson.homelinux.net
Wed Jun 30 08:31:11 CDT 2010


On Tue, June 29, 2010 22:16, Jefferson Ogata wrote:
> On 2010-06-30 01:53, J. Epperson wrote:
>> On Tue, June 29, 2010 21:27, Jefferson Ogata wrote:
>>>> Number  Start       End         Size        Type     File system
>>>> Flags 1      63s         401622s     401560s     primary  ext3
>>>> boot 2      401625s     139299608s  138897984s  primary  ext3 3
>>>> 139299616s  143380124s  4080509s    primary               swap
>>> I would say those end sectors on partitions 1 and 2 should be one
>>> less than the following partition's start sector. The end sector of
>>> partition 3 looks correct; though the last sector on the disk is
>>> 143380479, when you round down to a cylinder boundary you end up at
>>> 143380124.
>>
>> I was thinking the same thing, but that's what the parted rescue
>> "found", so I assumed it was correct.  Looking at another F12 system,
>> what you say is how that one is.  Not sure what to do, try it as is or
>> make the adjustment.  I do notice from the other system that I should
>> probably mark the swap as FS type linux-swap(v1).  The other system
>> looks like:
>
> I don't think it would actually matter with partition 1. If your
> filesystem has a 2kB or 4kB block size, then those extra 2 sectors won't
> ever be addressed. With partition 2, however, the additional 7 sectors
> extend the volume by one or two filesystem blocks (with 3 extra sectors
> on the end).
>
> I would go ahead and extend the partitions to the n-1 values. It's always
> safe to have a filesystem on a block device that is larger than the
> filesystem, but the converse is not true. You can also check the
> superblock with tune2fs -l to see how big the filesytem thinks the block
> device is. "Block count" * "Block size" / 512 should be <= the number of
> sectors.
>

I understand and will take that advice.  Hilariously, although gparted
blithely let me blow away the previous partition table without a whimper
and parted let me build a new one with the partitions mounted, parted now
refuses to let me adjust the partition end points because they are
mounted.  I suppose I could blow the whole thing away again and redo from
scratch, but I think I'm going to boot rescue and do with it with them not
mounted.




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