Turning drives on and off

mathias · Post by **mathias** » Sat Oct 23, 2004 4:32 pm

I heard serial ATA is or will be hot swapable, if so I think it would be really useful to use this to have some switches at the front for turning hard drives on and of while the PC is on. Unless this can already be done with software.

Even if this can't be done with the PC on, a switch for connecting/disconecting the power to the drive before turning could be useful. My JVC motor spinpoint was getting so anoying I decided to keep it disconnected most of the time and just use it for backup and storing files I won't access frequently(at least this way it won't wear out and the PSU can't kill it); my case is easy to open and close, but one that wasn't would be a problem.

Special separate (fanless)PSU's for hard drives would be useful for preventing a faulty PSU from taking out multiple drives, plus it would take a bit of load of the main PSU.

Sam Williams · Post by **Sam Williams** » Sun Oct 24, 2004 4:24 am

How about just letting Windows power management do it's job and spin down the HDD after being idle for a pre-defined amount of time?

YMMV, but I haven't found it to work very well. The drive spins down alright, but there always seems to be some process or other which wants to access it. The drive ends up spinning up and down every few minutes, which must be more damaging than leaving it running constantly.

Also, it seems more efficient to have manual control. I use SSSleeper to switch my screensaver on manually for the same reason; if I know I'm not going to use something for a while, I like to kill it straight away rather than wait for the timer. Again, YMMV there.

Tibors · Post by **Tibors** » Sun Oct 24, 2004 5:44 am

There are some fairly long threads on the forums of people who unsuccessfully tried to use windows power management to stop drives.

The idea for a switch sounds good, but... The SATA power connectors have a different length copper strip for the ground wires as the other wires. So the ground wires are always connected before the plus wires. How could you implement this with a switch, without resorting to using two switches

Bluefront · Post by **Bluefront** » Sun Oct 24, 2004 6:31 am

I'm doing the off/on thing right now with an external USB drive. It's internal power supply can be switched using a power control center that the monitor sits on. If I need to use the drive, I hit the switch, wait a few seconds, there it is.

Phill77 · Post by **Phill77** » Sun Oct 24, 2004 8:46 am

Tibors wrote:The SATA power connectors have a different length copper strip for the ground wires as the other wires. So the ground wires are always connected before the plus wires. How could you implement this with a switch, without resorting to using two switches

It wouldn't hurt to leave the grounds permanently connected, only need to switch the lives. Use a dual pole single throw to turn off the 5v and 12v at the same time. Been thinking of trying this myself for quite a while.

Mats · Post by **Mats** » Sun Oct 24, 2004 9:03 am

Speaking of SATA power connectors, does anybody know why there are so many pins? The general answer is maybe "for additional functions in the future", though I really can't understand what functions they could add to the power connector.

peerke · Post by **peerke** » Sun Oct 24, 2004 10:36 am

Would the powerswitch idea also work for a normal IDE-drive? I have been thinking of using a power switch to only turn on a backup/storage drive on start-up when I need it. This is usually after a few hours of photoshopping when I want to write the results from the workhorse-drive to the big storage-drive. I know I need to restart the computer because IDE isn't hot-swappable. Am I correct in thinking that switching the power off would make it completely invisible?

bomba · Post by **bomba** » Sun Oct 24, 2004 7:01 pm

I hot plug/hot swap a standard IDE desktop drive, but it's pretty involving. The drvie is installed in a Kingwin mobile rack (removable HD rack) in a 5.25" bay. However, since IDE drives are not hot swappable, I mounted a IDE to SATA converter on the back of the mobile rack. I also modified the wires carrying power to the IDE to SATA converter so that power to the converter is switched off when the key for the mobile rack is turned. Thus, when the key is turned, power to both the IDE HDD & IDE to SATA converter is switched, simultaneously. Ok, I then found that ICH5 does not support hot swap. Purchasing an inexpensive Silicon Image 3112A based pci SATA RAID controller fixed this problem. Works flawlessly now.

When I want to use the drive, I just turn the key, it is automatically recognized and insalled by WindowsXP. When I'm done, I uninstall the drive in device manager, then turn the key to power it off. This thread may also be of interest.

Jan Kivar · Post by **Jan Kivar** » Mon Oct 25, 2004 6:07 am

Mats wrote:Speaking of SATA power connectors, does anybody know why there are so many pins? The general answer is maybe "for additional functions in the future", though I really can't understand what functions they could add to the power connector.

These quotes are from the SATA I Spec Rev 1.0:

The comments on the mating sequence in Table 3 apply to the case of backplane blindmate connector only. In this case, the mating sequences are:
(1) the ground pins P4 and P12;
(2) the pre-charge power pins and the other ground pins; and
(3) the signal pins and the rest of the power pins.

There are three power pins for each voltage. One pin from each oltage is used for precharge in the backplane blind-mate situation.

Basically, there are three pins for each voltage (3.3V, 5V and 12V), and five GND pins, two of which are the "first mate" pins. One pin of each voltage pin group is used for pre-charge; which is necessary for hot-swapping, as the backplane connects both power and data "cables" at the same time.

Cheers,

Jan