Well, there goes Windows!

Garrett Cooper yanegomi at gmail.com
Mon Aug 22 00:04:47 UTC 2011

On Sun, Aug 21, 2011 at 5:00 PM, Nathan Whitehorn
<nwhitehorn at freebsd.org> wrote:
> On 08/21/11 18:11, Marcel Moolenaar wrote:
>> On Aug 21, 2011, at 2:32 PM, Nathan Whitehorn wrote:
>>> gpart does not support (well, anyway) changing the underlying partition
>>> table format without committing changes. Replacing the partition scheme,
>>> which this does, is such an operation.
>> Weird. I could always destroy tables, create new ones using a
>> different scheme and populate it with partitions without there
>> being a single write to disk. The commit/undo logic worked
>> just as well for those operations as the simpler ones. Did that
>> get broken or are you just mistaken?
> No, it's stupider than that. When you destroy a gpart without committing,
> the GEOM itself lingers as a (none)-type partitioning. This of course makes
> sense, since that ghost geom is what is maintaining all the state, but
> sometimes causes problems. For instance, it breaks some of  my lazy code
> that identifies non-partitioned disks by seeing if there is a GEOM there.
> But, while slightly more complicated to detect, this would not be too
> difficult to fix.
> The larger problem is that this behavior means that destroying gparts
> sometimes doesn't work at all. For instance, if you have nested partitioning
> like MBR+BSD (or EBR) it is not possible to destroy the underlying MBR geom
> without committing the destruction of the BSD geom. This is because the MBR
> geom cannot be destroyed, even without committing, while it continues to
> have children, which it does due to the ghost geom for the BSD slice.
> The regular partitioning editor only commits early in this particular case,
> and asks about each subpartition tree separately with a big scary dialog
> box. In the spirit of the autopartitioner, it makes one large scary dialog,
> and always runs in early commit mode instead of potentially showing many
> scary dialogs about partitions the user doesn't necessarily even know about.
> This behavior could be changed, but I think is the most friendly for the
> case in question: namely, "I want to blow away everything and let the
> installer handle all partitioning details by itself".

    I think that adding more bold text would better underline the fact
that you _are_ in fact going to blow away your partition tables..

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