Obviously a type 2.) solution from my previous post now exists
Back in October 2010 I bought one of these:http://www.ebay.com/itm/9-5mm-2nd-SATA- ... 483f91461b
This unit is 9.5mm thick, so it wont fit in the bay, but it was the thinnest available in 2010. I removed the circuit board (it has the required 50pin IDE connector, SATA connector & PATA to SATA bridge chip) and was able to fit it into the X301 bay. The board itself is ~7mm thick at the IDE connector.
I did not have a 7mm HDD on hand to test it though. I planned to buy a SATA extension cable to test it with a standard 2.5" HDD, but never did...
The plan was to buy an X300/X301 bay travel adapter like this "blank CD bezel":http://www.ebay.com/itm/260900639263?ss ... 1423.l2649
And then modify it to be somehow able to fit the circuit board (with hot glue) & 7mm HDD.
Since this seemed to be quite messy (the two support beams in the middle would have to be cut off) & the end product would be flimsy at best, I did not pursue it further.
I did test the caddy in the optical bay of my trusted old Dell D600 with an old (2006) 5400 RPM HDD. The highest transfer speed I got was 30MB/s, but this was limited by the old HDD & old computer, not PATA to SATA bridge.
And now we finally have the X301 bay HDD caddy available as a finished product
The one from Deyi & the one on eBay (Nimitz?) look similar, if not identical...
I did measure the power consumption though. The caddy alone consumes ~0.7W (the SATA to PATA chip is active even with no HDD in the bay). Since the D600 has hot swap (X301 does not), you can disable (remove device) the bay adapter & the HDD stops and power consumption of the bay hdd goes to zero (same as if physically removing it).
Since X301 does not have bay hot swap, it would be interesting to know if disabling the hdd (or bridge chip) in device manager reduces power consumption (without actually pulling the caddy out) - important when your battery is running out...sonysg
& others: can you measure the power consumption of the hdd+caddy & caddy alone?
I assume it is still in the range of HDD consumption + 0.7W for the bridge chip.
Can you also try to disable it in device manager & check if the power consumption drops?