Re: [gentoo-user] Big USB disks

[Peter Humphrey <peter@prh.myzen.co.uk>]

On Tuesday, 22 December 2020 15:32:27 GMT Rich Freeman wrote:
> On Tue, Dec 22, 2020 at 7:58 AM Peter Humphrey <peter@prh.myzen.co.uk> 
wrote:
> > Just a quickie - is there a way to enable a machine built on an MSDOS BIOS
> > to recognise a partition on a 4TB external disk? I think I know the
> > answer already, but just in case...
> 
> I suspect most newer firmwares are fine with it (even in legacy mode),
> and ancient ones would need a firmware update, so good luck with that.

As I expected...

> You might be able to mitigate the issue with a boot partition close to
> the start of the disk.  I'm honestly not sure if that works with
> something like a USB hard drive.  I'm not sure how old this system is
> either.

I wondered about that. I'm nervous, though, because this is my ultimate backup 
disk, and of course I don't want to endanger it. This disk is an external USB 
unit, not for booting from.

Mr Google tells me the model was releases in 2007. I will have bought it 
within a year or so of that.

> Back in the day MBR patches for large disks were a pretty common
> thing.  I'm not sure how much any modern OS depends on the firmware to
> do disk IO once it is booted, and I'm not sure that most bootloaders
> even need help from the firmware beyond maybe whatever goes in the
> boot sector.  This is why some GRUB modes require a secondary
> partition near the start of the disk to handle certain
> filesystems/etc.  (Or at least used to - GRUB and EFI have gotten so
> good that I don't pay much attention to that stuff on newer hardware
> and with common filesystems, even including ZFS.)

Thanks for the extra detail, Rich.

-- 
Regards,
Peter.