hard drive power sequencer, hard drive startup sequencer

[Timothy Daniels]

I have a card that is used for that purpose. It connects
in line with the power to a drive and delays the feeding
of power on startup.

There you are! OK, where did you get it? Is it still
available? Does it work with up to 4 IDE hard drives?


*TimDaniels*

 

[Barry OGrady]

There you are! OK, where did you get it? Is it still
available? Does it work with up to 4 IDE hard drives?

It was installed in an old mini computer that had a full height
40 meg hard drive. Oddly enough it wasn't being used. it was just sitting
there. It's only for one drive. I have no idea where to get one now.

It could be built quite simply. Just a delay circuit switching a relay.

*TimDaniels*

-Barry
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[Rod Speed]

It was installed in an old mini computer that had a full height
40 meg hard drive. Oddly enough it wasn't being used. it was just sitting
there. It's only for one drive. I have no idea where to get one now.

It could be built quite simply. Just a delay circuit switching a relay.

Trouble is that by the time all 4 drives have been spun
up, the bios has stopped checking for IDE drives visible.

You could kludge it massively by having that card also just
hit the system reset line again after all drives were powered
up, so the bios goes thru the check for visible drives again,
but thats a massive kludge when it makes a hell of a lot more
sense to just use an adequate power supply so you dont need
to sequence the drives at all.

 

[Timothy Daniels]

"Rod Speed" opined:

....it makes a hell of a lot more
sense to just use an adequate power supply
so you dont need to sequence the drives at all.

I agree. But yimminy, it ain't "elegant".
I wonder what the effect is, after all, of a
voltage sag on start up. Are any ungood
"consequences" likely?


*TimDaniels*

 

[Rod Speed]

Rod Speed wrote

I agree. But yimminy, it ain't "elegant".

Lot more elegant than that collosal kludge that resets the
system after the last drive has been powered up so the
bios can scan for drives present with all drives powered up.

I wonder what the effect is, after all, of a voltage sag on start up.

That can be bad for the drives.

Are any ungood "consequences" likely?

Yes, and some drives will just shut down when they see the
12V rail drop below what they consider to be acceptible.

They wont necessarily keep checking that in case the sag is temporary.

 

[shmoe]

It basically interrogates the drive on its details. Since the
drive is powered up and is itself waiting till the drive spins
up, it works fine. The bios doesnt wait forever and its very
unlikely indeed to still be polling for drives at the time that the
last drive of the 4 has been powered up by a power sequencer.


Yes, but the drive electronics is obviously up and it can
take a second or so to reply to the request for its details.


Not really. Initially the bios interrogates the drives on
their capabilitys, as part of the AUTO config mechanism,
and once its determined what drives are connected, then
just reads the MBR off the drive its been told to boot off,
identifys the partition to boot from and starts doing that etc.


Yes, there isnt any technical reason why say you
couldnt specify in the bios to allow say 10 secs for
all the drives to have spun up, but few bios have that.

Makes a hell of a lot more sense to just get a better
power supply instead of farting around like that, and
thats why few bios have anything like that.

SCSI drives do have that capability, and the
bios on the SCSI card allow for that capability.

I've got a funny drive that has a problem starting up sometimes. It
squawks real ugly, and then in a few seconds you can hear it click and
spin up. System boots up fine. But it's not the boot drive (one of
three in there). I set the bios memory test to the long version to
give the drives time to get up and running.

I was pretty annoyed with the last couple of drives I bought, the
power connector is getting to be a little too cheap and flimsy these
days. You can feel the frail little bastard flexing when you push in
the powersuppy connector. Not surprising if they go bad. Suckers
used to be rock solid. Cheap bastards

 

[Rod Speed]

I've got a funny drive that has a problem starting up sometimes. It
squawks real ugly, and then in a few seconds you can hear it click and
spin up. System boots up fine. But it's not the boot drive (one of
three in there). I set the bios memory test to the long version to
give the drives time to get up and running.

I was pretty annoyed with the last couple of drives I bought, the
power connector is getting to be a little too cheap and flimsy these
days. You can feel the frail little bastard flexing when you push in
the powersuppy connector. Not surprising if they go bad. Suckers
used to be rock solid. Cheap bastards

Thats more the printed circuit board that the power connector is soldered to.

Yes, some are a significant worry on that score. Plenty arent tho.