Re: How to use dmsetuup?
Andy Smith <andy@strugglers.net> wrote:
> Hello,
>
> On Wed, Nov 08, 2023 at 05:19:01PM -0700, Tom Dial wrote:
> > On 11/7/23 17:19, gene heskett wrote:
> > > What do I do if a gpt partition table has already been made and
> > > an ext4 system is already installed? IOW just how "bare" a disk
> > > is needed? Is writing a null gpt sufficient?
>
> > You can ignore them, or not, as you like. If you want, you could
> > overwrite them with zeros or a pattern of your choice; I would not
> > bother.
>
> You do need to be very careful if you have put a GPT label on a
> device and then incompletely wiped the device in order to use it for
> something else that doesn't involve a GPT label.
>
> The reason for that is, there are several motherboards (EFI
> firmwares?) out there that consider a missing GPT label with a
> backup GPT present to be an indication that the device is corrupt.
> They then helpfully copy the backup GPT back to the start of the
> disk, corrupting any data that was there already.
Yes, that kind of thing is why I always put a couple of small, unused
partitions at the start and end of a disk that's to be used for LVM.
Partition the disk as normal using GPT and then put LVM on the middle
partition.
> Example:
>
> https://news.ycombinator.com/item?id=18541493
>
> "wipefs -a /dev/sda" shold clear the GPT without having to write to
> the entire device.
>
> Thanks,
> Andy
>
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