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Re: Support for hard drives > 2 TB?

from "Michael van Elst" <>:

> ("Thomas Mueller") writes:

> >I wouldn't need the boot partition to boot > 2 TB.  I would have a 
> >partitioning scheme like

> Booting probably requires 512byte sectors.

> >1: FreeDOS <= 8 GB (so FAT32 cluster size can be 4 GB)

Here I meant for the cluster size to be 4 KB, not 4 GB.

> FreeDOS requires a classic MBR and 512byte sectors. The
> MBR then limits you to 2TB.

I think, though I may remember wrong, that GPT allows a traditional MBR for 
OSes that don't recognize GPT, and data to be accessed by those OSes, but such 
an OS can access only 2 TB.  I don't want more than 8 GB for FreeDOS.  But I 
think on the newer computers, BIOS recognizes USB, so that I could run FreeDOS 
from a USB stick.  I think the big-drive firmware can make sector size look 
like 512 bytes?

> >2: NetBSD, subdivided for swap, /home, maybe /boot, /, maybe /usr (not in 
> >that order)

> You could add a GPT, this would make the whole disk accessible
> to NetBSD. However, the GPT standard wants a dummy MBR that
> prevents GPT-non-aware tools from trying to use the disk. This
> is not really a problem, except for standard tools that just
> overwrite your MBR when you write the GPT and vice versa.

> Booting is still done from the MBR. The bootcode can use
> a disklabel (or the default disklabel computed from MBR)
> to find the root partition. This must be within the first
> 2TB and you need to guarantee the proper alignments between
> MBR, disklabel and GPT partitions.

> It is probably easier to boot the kernel from FreeDOS using
> dosboot(8).

Or if dosboot doesn't work, as it hasn't since 5.0.2, I can make a giant floppy 
image, like 30 MB, newfs for ffsv1, copy the necessary boot, and installboot, 
then copy the desired kernel(s): copy image to a DOS or ext2fs partition and 
boot using grub4dos.  grub4dos can read an ext2fs partition even if the rest of 
DOS can't.

> There was some effort to create a GPT aware bootloader,
> but I don't know the results.

> >3: FreeBSD

> dunno

I think now FreeBSD supports hard disks > 2 TB.

> >4: Extended partition with logical partitions for swap, /home, possibly more 
> >than one Linux (one would be Gentoo), maybe nonbootable extra data 
> >partitions (try xfs?).

> Linux could probably use the same GPT. Again this is probably
> a problem with the partitioning tools.

> Linux however already has a GPT aware bootloader.


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