Switching Power of hard drives ON and Off

I question the wisdom of switching off only 12 v, and I presume leaving +5 v, if I understand what you are proposing.

May I recommend this $7.95 solution?

Or I am sure you can find better quality ones from many sources.

Alternatively, look at a USB external case for your IDE drive. Here is one for Firewire and/or USB. No reboot and "BIOS screwing" required.

Thanks, Steve

I am already using two USB drives and one of the drives that I want to stop is a serial and they don't work on the available boxes.

Thanks

Vlad

I too. In general, unless the equipment specifically states that it is safe to switch off some of the supply voltages, I wouldn't recommend it. Not only might the equipment be damaged (though probably unlikely), but there could be peculiar behavior of anything attached to it (in this case, the computer).

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Vlad,

Well, I guess I didn't have all the facts??

Here is a USB to SATA case.

Add a USB hub if you need to. Google helped find it.

Or use the SATA interface directly, if the rest of your system has an external SATA connection. (And if it does, then there are cheaper SATA only external cases. Google for some.)

Still confused as to why, then, the $7.95 solution won't work for one drive, which, I assume, perhaps incorrectly, is IDE?

Please let "suggest" again that the 12 v switching isn't recommended. But maybe it will work. Prove me wrong. Report back to the group your results. Be sure to mention what drives you are talking about, exactly, since maybe what works for brand X, model Y, won't work for brand Z, model A. We'll all learn, which is the idea here. If it is a viable and universal solution, someone somewhere would be doing it commercially, which I'm quite unaware of.

Good Luck and Thanks, Steve

Believe what you want - simply switching the 12V supply is asking for trouble. If your going to switch, you need both the +5 and the +12 supplies or you'll end up with a zapped drive.

But the drive will still be connected; if the +5 is still active so would

90% of the electronics (if drives were to work as simply as you suggest), so it would be recognized in the BIOS.

Lots.

so what happens when windows puts the drive in power down mode...

i think the key is you want to make sure the heads are parked before you spin down the disc, but you said you would only operate the switch when the computer is OFF.

I say try it.

Mark

Have a guess. I'll give you a big clue - Windows can't somehow disconnect the power leads to the drive.....

So what? It's not the electronics that wear out. That may be good enough if you're really worried about the life of the drive.

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Why don't you just have the software spin the drive down after a period of inactivity?

On Thu, 31 Mar 2005 01:20:02 GMT, "Ivor Floppy" put finger to keyboard and composed:

If you disconnect the +5V supply, you may then have an improperly terminated IDE cable. I suspect this may cause problems with reflections.

I know some drives (eg the old Quantum Fireball) make use of "discware", so an unreadable platter may cause the HD to be invisible to the BIOS.

I also seem to recall that a HD is invisible when it fails to spin up due to stiction.

- Franc Zabkar

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On 30 Mar 2005 19:23:58 -0500, Sam Goldwasser put finger to keyboard and composed:

I suspect the +12V rail merely powers the mechanical assemblies. A healthy +5V rail would probably guarantee the drive's sanity, and would probably be sufficient to ensure that the IDE interface was not in a "hung" state. Having said that, I wonder if any chip that expects dual supplies could be damaged by latchup?

- Franc Zabkar

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YES yes yes James!

That is the best idea but unfortunately Windows XP turns off ALL the drive/s not only the ones we want. So if the XP can spin down the drives may be there is a software way to spin down the ones you want. It should include "serial" and external drives, if possible. If such program doesn't exist, it may be created. There is a need for that. If we stop the drive/s used for a backup, that in my case is once a week, the drive should last 5 to 7 times longer. Ideally it should control the BIOS because the hardest action on the drive is the starting.

Thanks to all of you Vlad

well it does "disconnet" the drive motor because it parks the heads and spins it down...

I know this "disconnect" happens within the drive itself and not within the power supply or the cable.

Disconnecting the 12V probably is about the same.... IF YOU PARK THE HEADS FIRST!

I suggest you test this on a drive that you don't care about first.

Mark

Thats quite an important difference. Telling the drive to stop (as Windows does) means the drive *knows* its not supposed to be running, and goes into sleep mode waiting to be awoken.

I doubt its anything like the same. The drive is expecting the 12V supply to be there - under all normal operational circumstances it would be, so there's no reason for the drive to have any form of protection or safety checking against such an event. As the drive will be assuming the 12V is present, it will be constantly trying to get the motor running, putting who-know-what strain on the motor drive circuitry.

.. nice get out clause there....:)

I just wonder if we disable a drive on BIOS it stops it from running ? I don't think so. It only prevents it from being accessed,

Vlad

That's interesting. I must try that. Thanks Vlad

Bad idea. The heads should be parked first. Some operating systems offer the option of turning off the hard drive(s) after a preset time interval.

Mark Z.

On Sat, 2 Apr 2005 05:26:33 -0600, "Mark D. Zacharias" put finger to keyboard and composed:

The OP understands that "the operation of those [+12V] switches should only be done when the computer is off".

In any case, if power is removed from the servo, the kinetic energy of the rotating platters will auto-park the heads.

- Franc Zabkar

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Every drive on the market has autoparked for at least 15 years now so as you say that's certainly not an issue. The last drive I had to manually park was a whopping 20 megabytes and was a 5.25" 2" high drive.

You're certainly right about the write cache though, fortunatly you can turn this off if you desire, but it does provide a performance boost.