Drive / partition / volume limits currently in place on a Tivo HD?

[ciper]

I have been away from the forums for a while due to health issues. In that time I was constantly annoyed by the limited amount of space on my Tivo HD (1TB), especially compared to the nearly limitless 700gb S1 that used to be my primary unit.

I tried searching the three forums (here, TCF and MFSLive) and the best thread I could find was this - http://mfslive.org/forums/viewtopic.php?f=11&t=257
It's very informative but I wonder how much of the information is still accurate.

My purpose for asking is that I spent the money and time to modify my Tivo HD to be able to run three internal drives internally, all of which are connected to the primary SATA interface and show up to my computer as a single 3TB drive.
Basically I am worried my efforts will be fruitless :( I was hoping to impress all of you with my design :o

So what is the maximum usable size of the A drive? How about the B drive? These answers will help me to figure out if I need to sell/return hardware to the store and your help is greatly appreciated.

[Jamie]

As of 9.x (I haven't checkedout 11.x yet):

There are signed int sector numbers in the tivo ide-disk.c driver that limits partition sizes to 1TiB. There's a custom kernel with a patch that fixes that here: link (http://www.dealdatabase.com/forum/showthread.php?p=299520#post299520).

In addition, the tivo software (aka tivoapp) seems to get confused when the total MFS media size is > 2TiB. I've seen various forms of crashes when attempting to build systems larger than that. It may work at first, but eventually they always crash and burn. I suspect there are various places in the tivo application code where 32 bit int sector numbers are used. The DiskConfiguration MFS objects are one such place. All the integer object attributes in MFS are 32 bit, AFAIK.

[ciper]

Without the patched kernel and taking the ~2TB max total size into consideration would it technically be possible to create a 2TB A drive assuming all of the individual MFS partitions were 900GB or less?

[Jamie]

Without the patched kernel and taking the ~2TB max total size into consideration would it technically be possible to create a 2TB A drive assuming all of the individual MFS partitions were 900GB or less?Yes. But I don't know of any existing tools that will do create such an MFS partition layout.

[Note that 2TiB (2 * 2^40) > 2TB (2 * 10^12)]