SSDs and HDDs

[Ralf Mardorf]

On Thu, 18 Feb 2016 20:05:56 +0100, Ralf Mardorf wrote:
>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.

PS:

I guess I understand now.

The BIOS not necessarily has got impact to the install. IOW when using
linux, the BIOS gets not in the way and the whole disk can be used, but
the boot is started by the BIOS and this might not be able to get
access to the whole disk.