various mishandlings of corrupt GPT

[Miloslav Trmač]

On Thu, Oct 24, 2013 at 4:59 PM, John Reiser <jreiser at bitwagon.com> wrote:
> On 10/24/2013 01:33 AM, Richard W.M. Jones wrote:
>> On Wed, Oct 23, 2013 at 10:49:35PM -0600, Chris Murphy wrote:
>>> So that's why I ask if it makes sense to have an fsck for GPT disks.
>>
>> Sounds sensible.  The "fsck" would just check the checksums of primary
>> & secondary tables, and if an error in either (but not both) is
>> detected it would restore from the other one?
>
> Such a tool also should diagnose both overlap and unclaimed space,
> and provide some means for repair of these conditions.
> For example in the case of "minor" overlap: repair might be "minimum wins",
> "maximum wins", or arbitrary edit of extent fields.
> The tool also should diagnose "protective MBR" situations and
> understand common values for partition type entries (both GPT and MBR).
> It should provide the ability to overwrite any existing checksum
> with the calculated correct checksum.  The tool also should be able
> to erase both GPT tables (overwrite all bytes to 0x00.)

Please let's not mix the two concepts of "tools" quoted above.

If the proposal is to run something by default on every bootup, it
must be overwhelmingly safe, not apply heuristics that may break the
system even more.
    Mirek