SSDs and HDDs

[blind Pete]

Ralf Mardorf wrote:

> 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.

Unless you have a very old BIOS that is not going to be a problem.  
Another reason for having /boot on a separate partition is if you 
are using RAID, but if you were doing that you would already know 
all this stuff.  

-- 
blind Pete
Sig goes here...