Where is a 'magic' number 2.2 came from ?
No one did post partitioning of the HR34 with 3 TB drive. I would say it's using 2 TB of total space these 3/4 TB drives.
Dish is supporting 3 TB for EHD.
No need to do "a significant firmware change" (why you exaggerating ?), just a few changes related to buffer size (512->4096) and corresponding use of it.
The MBR can only support 2^32 unique LBAs, because it only supports 32-bit values for them.
2^32 * 512 bytes/sector = 2.2 TB. No partition can go past the 2.2 TB point on the hard drive when using MBR.
You need to replace the MBR with a GPT, update all the built-in disk tools (ex. gdisk not fdisk) accordingly, and whatever little misc. things the software and/or firmware might need to get it to work. It's not trivial, especially when trying to do it remotely for millions of customers with existing boxes full of recordings they'd like to keep.
It's a lot easier to do what D* did -- create a new branch of software for a new device and have that device support it from its initial release.
It was thought that advanced format drives would set this limitation to 17.6 TB, but to make them backward compatible they emulated 512 bytes/sector. Each one of those emulated sectors needs a unique LBA entry, and you have the same exact problem.
The THR22-100 (and all Tivos) have the same problem, as the Apple Partition Manager is also limited to 32-bit LBA entries.
Edited by bobcamp1, 05 October 2012 - 02:15 PM.