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Re: Won't boot if /, home, swap are encrypted

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Le 22/10/2018 à 17:49, David Wright a écrit :
> On Mon 22 Oct 2018 at 14:42:09 (+0200), Pascal Hambourg wrote:
>> Le 22/10/2018 à 05:50, David Wright a écrit :
>>>
>>> Noted above. This is to give you partition alignment of 1MiB for
>>> efficiency. For GPT disks like this, I also add a 3MiB partition
>>> (giving me 4MiB alignment) set to "BIOS boot" which, like it says,
>>> allows it to be booted in legacy mode if ever required.
>>
>> Why do you need 4 MiB alignment ?
> 
> As you probably know, I don't.

No, I didn't know, so I was curious. You may use an SSD with an uncommon 
4 MiB erase block size. Less than one hour after I posted the question, 
I read a post from someone who considered converting partitions into LVM 
logical volumes without moving data and was fortunate they used 4 MiB 
alignment, as LVM uses 4 MiB blocks (extents) by default.

> Is there any harm in always rounding up?

It wastes space.

> I'm just generous to Grub and its ilk.

GRUB does not even need a MiB BIOS boot partition. AFAICS, the biggest 
generated core image embedding all required drivers fits into 128 KiB.

> When you read posts about
> partitioning, you realise there are some really stingy people out
> there. They would probably be calculating a size that squeezes it into
> the space before 1MiB.

This is what I do when converting a disk from DOS/MBR to GPT. There is 
plenty of space for a BIOS boot partition between the GPT partition 
table and 1 MiB, and the BIOS boot partition does not need to be aligned 
(no write performance issue).

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Thread

Won't boot if /, home, swap are encrypted D&P Dimov <lddimov@yahoo.com> - 2018-10-21 15:30 +0200
  Re: Won't boot if /, home, swap are encrypted Matthew Crews <mailinglists@mattcrews.com> - 2018-10-21 15:40 +0200
  Re: Won't boot if /, home, swap are encrypted Roberto C. Sánchez <roberto@debian.org> - 2018-10-21 19:40 +0200
    Re: Won't boot if /, home, swap are encrypted D&P Dimov <lddimov@yahoo.com> - 2018-10-21 19:50 +0200
    Re: Won't boot if /, home, swap are encrypted Matthew Crews <mailinglists@mattcrews.com> - 2018-10-22 02:10 +0200
      Re: Won't boot if /, home, swap are encrypted D&P Dimov <lddimov@yahoo.com> - 2018-10-22 04:20 +0200
        Re: Won't boot if /, home, swap are encrypted David Wright <deblis@lionunicorn.co.uk> - 2018-10-22 07:10 +0200
      Re: Won't boot if /, home, swap are encrypted David Wright <deblis@lionunicorn.co.uk> - 2018-10-22 06:00 +0200
        Re: Won't boot if /, home, swap are encrypted Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-10-22 14:50 +0200
          Re: Won't boot if /, home, swap are encrypted David Wright <deblis@lionunicorn.co.uk> - 2018-10-22 18:00 +0200
            Re: Won't boot if /, home, swap are encrypted Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-10-22 19:50 +0200
              Re: Won't boot if /, home, swap are encrypted Joe <joe@jretrading.com> - 2018-10-22 19:50 +0200
                Re: Won't boot if /, home, swap are encrypted Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-10-22 20:10 +0200
              Re: Won't boot if /, home, swap are encrypted David Wright <deblis@lionunicorn.co.uk> - 2018-10-23 04:30 +0200

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