Right, I've done a bit of reading and it's all to do with the Logical Block Addressing (LBA) entries in the partition table of the Master Boot Record (MBR). The LBA entries use 32 bits to declare the first sector (let's call it a sector) in each partition, and another 32 bits to declare the number of sectors in the partition. CHS (cylinder, head, sector) addressing only has 24 bits available, and is now totally superseded.
First off, it is possible to define partitions in the LBA to occupy an (almost) 4TB disk with 512-byte sectors. The first three partitions would have to fill the first 2TB, and then the fourth partition would be (almost) 2TB in size (2^32-1 x 512) starting at sector 2^32-1. From Wikipedia:
However, in practice, only certain LBA-48 enabled operating systems, including Linux, FreeBSD and Windows 7 that use 64-bit sector addresses internally actually support this. Due to code space constraints and the nature of the MBR partition table to only support 32 bits, boot sectors, even if enabled to support LBA-48 rather than LBA-28, often use 32-bit calculations, unless they are specifically designed to support the full address range of LBA-48 or are intended to run on 64-bit platforms only. Any boot code or operating system using 32-bit sector addresses internally would cause addresses to wrap around accessing this partition and thereby result in serious data corruption over all partitions.
I believe the Humax OS is based on Linux, so it might
be able to support this - but it is irrelevant because (for the HDR-FOX) we would need the main recording partition to fill most of the disk.
With regard to redefining the sector size, so that (for example) 2^32 sectors x 4096 bytes = 16TB, Wikipedia says this:
Versions of Windows more recent than Windows XP support the larger sector sizes as well as Mac OS X, and the Linux kernel has supported larger sector sizes since 2.6.31 or 2.6.32, but issues with boot loaders, partitioning tools and computer BIOS implementations present certain limitations, since they are often hard-wired to reserve only 512 bytes for sector buffers, causing memory to become overwritten for larger sector sizes. This may cause unpredictable behaviour as well, and therefore should be avoided when compatibility and standard conformity is an issue.
In short, it doesn't look like a totally dead duck... yet.
I think it would be useful to split this topic with post 35 starting a new topic "Installing a Drive Larger Than 2TB", with a note edited into the start of the first post that it is a continuation from this topic (with a link back to post 34).