SSDs and HDDs

[Ralf Mardorf]

On Thu, 18 Feb 2016 10:45:13 -0500, Gene Heskett wrote:
>> >You are correct, but since most users do not need to have a separate
>> >boot partition (and Ubiquity will not give them one by default) then
>> >this will not affect them.  
>>
>> That's good. I had the wrong impression /boot by default gets it's
>> own partition.
>
>That depends on the bios of that motherboard.  I have been forced to 
>create and use a /boot partition as the FIRST patition on the disk by 
>bios limitations, the reasoning being that most installers put the
>boot stuff on the disk last, presenting the spector of having the
>stuff needed to boot, too far into a big disk that particular bios
>never dreamed about, so the bios disk read calls needed to boot it,
>can't reach it, too far into the disk.

Hi Gene,

assumed there is such a hardware-bios-issue that requires to boot from
the first partition, why makes it a difference if /boot is on a
separated partition, instead of the root directory including /boot on
the first partition.

IOW what's the difference between

/dev/sda1 /boot
/dev/sda2 /

and

/dev/sda1 /      including the /boot directory

?

I understand, the logic behind this is, that if the /boot directory and
it's content is written at the end of the install, the assigned
addresses are out of reach for the bios, so the bios can't write the
data. However, if you ensure that /boot is written at first, what
happens to anything else?

If everything is on / and you have got a 10 TiB drive, but you're using
MBR, then I suspect you simply can't use the remaining TiB [1]. IOW if
you format a partition, you can't format it to anything out of reach.
What you are able to format, should be accessible.

Regards,
Ralf

[1] "maximum addressable storage space of a 512-sector disk to 3.99
TiB" - https://en.wikipedia.org/wiki/Master_boot_record

Good news for me, I didn't remeber correctly, I thought the limit is
1 TiB. I prefer using MBR and thought I can't use more than 1 TiB
when using MBR.