Re: Possible bug in mkfs.ext3

jd1008
Sat, 20 Sep 2014 18:38:18 -0000

The -S was advised by a member of the Fedora Users Mailing List,
and I thought I would try it.
I still have the original disk, so no permanent harm.
I keep trying what is suggested on a copy of the partition.

Only drag is the copying :)
It is a 400GiB partition (400 * 1024^3).

I am currently scanning the parition for a superblock, starting at -b 0,
and keep incrementing by 512, until I find what"might be" a
superblock;
i.e. fsck does not say "Bad magic number". Of course, that's no
guarantee
it is a superblock, but it gives me an opportunity to examine the superblock
at that offset.

Regards,

JD


On 09/20/2014 12:14 PM, Theodore Ts'o wrote:
> On Fri, Sep 19, 2014 at 07:56:37PM -0600, jd1008 wrote:
>> I am reporting this on the advice of the Fedora Users Mailing List
Member.
>>
>> This the mailing list exchange outlining the problem with specifying -S
to
>> mkfs,
>> and it's subsequent consequences when fsck is run.
> If none of the possible superblocks are valid when using mke2fs -b
> <NNN>, there's a good chance that your partition table (or LVM
> metadata) has gotten corrupted.  You should definitely check to make
> sure the partition setup is sane before trying to use mke2fs -S.
>
> It's also true, as Andreas has stated, that with the large number of
> new file system options and layouts with ext4, mke2fs -S is much more
> hazardous unless you __really__ know what you are doing.  It would
> probably be a good idea to have some warning messages to that effect
> in the man page.
>
> 						- Ted
>