Date: Sun, 21 Aug 2011 17:04:45 -0700 From: Garrett Cooper <yanegomi@gmail.com> To: Nathan Whitehorn <nwhitehorn@freebsd.org> Cc: freebsd-current@freebsd.org, Marcel Moolenaar <marcel@xcllnt.net> Subject: Re: Well, there goes Windows! Message-ID: <CAGH67wT4KtRsWrw1n08X9NS8LxCeRjNzwPUZ=f%2BsyN2321LJgA@mail.gmail.com> In-Reply-To: <4E519C13.4060700@freebsd.org> References: <CAGH67wRFP9nFQLr0Gh-h4rKWrndZSy=6Q%2BKLC_U5Fg4RD%2BJMCw@mail.gmail.com> <4E4DB9A7.4040404@freebsd.org> <CAGH67wQoXOju3=OTh%2B6JoKLxkp7Vzqu8vg%2BO9X=DPXB5EkBJtQ@mail.gmail.com> <4E517978.2020705@freebsd.org> <64622705-80AB-4FEF-91E9-8F3041818B4E@xcllnt.net> <4E519C13.4060700@freebsd.org>
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On Sun, Aug 21, 2011 at 5:00 PM, Nathan Whitehorn
<nwhitehorn@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 mak=
es
> sense, since that ghost geom is what is maintaining all the state, but
> sometimes causes problems. For instance, it breaks some of =A0my lazy cod=
e
> 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 partition=
ing
> like MBR+BSD (or EBR) it is not possible to destroy the underlying MBR ge=
om
> without committing the destruction of the BSD geom. This is because the M=
BR
> 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 cas=
e,
> and asks about each subpartition tree separately with a big scary dialog
> box. In the spirit of the autopartitioner, it makes one large scary dialo=
g,
> and always runs in early commit mode instead of potentially showing many
> scary dialogs about partitions the user doesn't necessarily even know abo=
ut.
> 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..
Thanks,
-Garrett
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