Thanks for the info! I used your guide and installed a 2 TB WD works great 
Why do you think that? I highly doubt they're using a one-time programmable ROM to store the OS.Its nice to hear the drive can be upgraded but bad to here the OS is on a chip, therefore meaning it more than likely cant be modified.
I didn't say it was or wasn't but the THR22 is the same hardware as the HR21/HR22 and the OS is on a chip not the hard drive.Why do you think that? I highly doubt they're using a one-time programmable ROM to store the OS.
That's what I'm saying.. if it is on a "chip" (which seems to be the case given the OP's success at cold-replacing the HD), that chip doesn't have to be one time programmable. I'd be willing to bet it's read/write and allows for OS updates.I didn't say it was or wasn't but the THR22 is the same hardware as the HR21/HR22 and the OS is on a chip not the hard drive.
And from DDB here are the partitions
sudo ./pdisk.x86 /dev/sdb
Edit /dev/sdb -
Command (? for help): p
Partition map (with 512 byte blocks) on '/dev/sdb'
#: type name length base ( size )
1: Apple_partition_map Apple 63 @ 1
2: Version 1 1 @ 2148865904
3: Rsvd 1 @ 2148865905
4: Rsvd 1 @ 2148865906
5: Rsvd 1 @ 2148865907
6: Ext3 mdi 15626240 @ 2148865908 ( 7.5G)
7: Ext2 Devl 524288 @ 2164492148 (256.0M)
8: Swap Linux swap 262144 @ 2165016436 (128.0M)
9: Ext2 /var 524288 @ 2165278580 (256.0M)
10: MFS MFS application region 589824 @ 2172094324 (288.0M)
11: MFS MFS media region 1733755196 @ 2173273972 (826.7G)
12: MFS MFS application region 2 589824 @ 2172684148 (288.0M)
13: MFS MFS media region 2 2148865840 @ 64 ( 1.0T)
14: Ext3 SQLite 6291456 @ 2165802868 ( 3.0G)
Device block size=512, Number of Blocks=3907029168 (1.8T)
DeviceType=0x0, DeviceId=0x0
I think what sk33t3r is talking about is user mods to the OS. Then again, you can't do that on any of the newer TiVos. While the s/w is still on the disk, the h/w verifies the signature.That's what I'm saying.. if it is on a "chip" (which seems to be the case given the OP's success at cold-replacing the HD), that chip doesn't have to be one time programmable. I'd be willing to bet it's read/write and allows for OS updates.
Thanks, I see what he was saying now. I took "modified" to mean modified at all, manufacturer included, which just wouldn't make sense. While user mods are more difficult with the OS stored on NAND/Flash/etc, it's still not impossible to read/write it. The integrity checks are still the limiting factor, as pointed out.I think what sk33t3r is talking about is user mods to the OS. Then again, you can't do that on any of the newer TiVos. While the s/w is still on the disk, the h/w verifies the signature.
Just to bump this thread 5 months later....Seagate Pipeline AV 500GB. I initially replaced mine with a Seagate Barracuda 2TB, but recordings kept stuttering and freezing. Thinking that the "power savings" features of that Barracuda were responsible, I bought a Pipeline HD 2TB (seems to be the same as Pipeline AV), only to have the same problems on HD recordings made over the next week. I just got back from a 12-day vacation and an HD recording made on the 30th was fine, while one made on the 24th was not. Will keep trying to see if this was a "teething" issue.
I understand that as stated above, it should be posible to dump the rom that has the os.The OS isn't on the disk for the THR22.