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




On Mon 22 Oct 2018 at 19:41:09 (+0200), Pascal Hambourg wrote:
> 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.

Sorry to make the assumption. For me, disks are spinning rust and SSDs
are something for the future. Perhaps. If I'm fortunate.

> > 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).

The ones I've converted were old/relatively small (≤2TB) and had the
first partition starting at the traditional 63, so I'm repartitioning
from scratch anyway. But I can't get worked up over the odd MB. I've
seen big disks where the first partition starts at 2048 which is 8MiB
for 4K sector size.

Cheers,
David.