> The SATA power connector supplies 3.3, 5 and 12v. A "complete" > solution will have all three. Most drives use just the 5v, so you can > probably ignore 3.3v and 12v. I'm not interested in building something that's going to work for every possible drive config- just my config :) Both the Intel X25-e and the OCZ only uses the 5V rail.
> You'll need to use a step up DC-DC converter and be able to supply ~ > 100mA at 5v. > It's actually easier/cheaper to use a LiPoly battery & charger and get a > few minutes of power than to use an ultracap for a few seconds of > power. Most ultracaps are ~ 2.5v and LiPoly is 3.7v, so you'll need a > step up converter in either case. Ultracapacitors are available in voltage ratings beyond 12volts so there is no reason to use a boost converter with them. That eliminates high frequency switching transients right next to our SSD which is always helpful. In this case- we have lots of room. We have a 3.5" x 1" drive bay, but a 2.5" x 1/4" hard drive. There is ample room for several of the 6.3V ELNA 1F capacitors (and our SATA power rail is a 5V regulated rail so they should suffice)- either in series or parallel (Depending on voltage or runtime requirements). http://www.elna.co.jp/en/capacitor/double_layer/catalog/pdf/dk_e.pdf You could 2 caps in series for better voltage tolerance or in parallel for longer runtimes. Either way you probably don't need a charge controller, a boost or buck converter, or in fact any IC's at all. It's just a small board with some caps on it. > Cost for a 5v only system should be $30 - $35 in one-off > prototype-ready components with a 1100mAH battery (using prices from > Sparkfun.com), You could literally split a sata cable and add in some capacitors for just the cost of the caps themselves. The issue there is whether the caps would present too large a current drain on initial charge up- If they do then you need to add in charge controllers and you've got the same problems as with a LiPo battery- although without the shorter service life. At the end of the day the real problem is whether we believe the drives themselves will actually use the quiet period on the now dead bus to write out their caches. This is something we should ask the manufacturers, and test for ourselves. -- This message posted from opensolaris.org _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
