Old thread but I have just come up against the same issue. My HDRFOX-T2 disk started giving errors and I had an old (seemingly identical) ST3500312CS 500Gbyte drive which I thought I would use. The drive worked fine in Windows and also as an external USB drive on the Humax but refused to be recognised as an internal drive. (No erasing, pre-formatting etc made any difference)
I had labelled it as being from an old PVR9300T.
Replacement drive
ST3500312CS s/no: 9VV5STP6 F/W : SC13 P/N: 9GW132-012
The existing failing drive was
ST3500312CS s/no: 6VVH6FHF F/W : SC13 P/N: 9GW132-191
HDPARM and SMARTCTL for the existing drive show
- Gen1 signaling speed (1.5Gb/s)
- Gen2 signaling speed (3.0Gb/s)
SATA Version is: SATA 2.6, 3.0 Gb/s (current: 3.0 Gb/s)
HDPARM and SMARTCTL for the ex PVR9300T drive show
* Gen1 signaling speed (1.5Gb/s)
SATA Version is: SATA 2.6, 1.5 Gb/s (current: 1.5 Gb/s)
i.e. no mention of 3.0Gb/s
So it would 'appear' that the HDRFOX-T2 checks the drive capability if it is internal and ignores it if it is not Gen2 but allows it for external drives to allow backups.
I haven't gone through the process of trying various kernels, this is with
Custom firmware version: 3.13 (build 4028)
Humax Version: 1.03.12 (kernel HDR_CFW_3.13)
Neither drives has any jumpers fitted but normally the jumper would force it to Gen1 mode anyway.
Pay me to be cheap but I don't have that much on the disk these days. Anyway, now bought a 1TB WD drive which of course is fine. Had to enter SAFE mode to format it, which I had forgotten about.....