On 01/04/2026 at 21:59, Yaroslav Halchenko wrote:
such setup is not supported by grub ATM. Hence I think it would be great if
user was warned and insisted to create /boot partition.
(...)
Here is a log from IRC with a recommended workaround:
(...)
15:30 Sledge: grub can't read an 8T disk in BIOS mode, that's your
problem
15:31 Sledge: to support big disks like that, you need a /boot
filesystem which lives entirely within the first 2T of each disk
As explained on IRC and demonstrated in QEMU with SeaBIOS, GRUB for BIOS
(grub-pc) itself can read disks up to 8TB and beyond via the EDD BIOS
disk interface (INT13h extensions) using 64-bit LBA (in comparison, the
PATA/SATA interface only uses 48-bit LBA). The 2TiB limit is in some
(most ?) BIOS implementations, probably because they internally use
32-bit arithmetics even though the EDD BIOS interface uses 64-bit LBA.
I wonder if d-i could add such safe-guards as "if /boot is on a partition
on GPT table and it is over 8T -- warning?"
I guess you mean "over 2TiB".
It is not that simple. If the filesystem is in a RAID array or a LVM
logical volume or is a multi-device btrfs filesystem, d-i (actually
partman) would need to check if underlying btrfs/RAID members or LVM
physical volumes extend beyond 2TiB.
