power output of scsi drives

[Julian Hales]

Hi all

At the mo i have a pc and in a seperate tower with a psu 4 scsi hard drives,
fair few years old, couple of 4gb and couple 9gb, only one spins at
10000rpm.

I have a seperate psu for these, i think a 200w

I want to add the same to another pc and feed off another psu.

Am i pushing my luck with this? i cant find any power usage for scsi drives,
guess the latest ones use more power.

im not too up on scsi but learning, the scsi ng which i have used on and off
for a couple of years dont like question like this or not too great at
offering advice.

Also cooling advice would be great, a couple of brand websites offer temps
to be kept at but how do i check these? I keep them on 24/7 unless im
watching a dvd on the pc next to it as they are pretty loud.

ME and SE machines.

thanks

 

[kony]

Hi all

At the mo i have a pc and in a seperate tower with a psu 4 scsi hard drives,
fair few years old, couple of 4gb and couple 9gb, only one spins at
10000rpm.

I have a seperate psu for these, i think a 200w

I want to add the same to another pc and feed off another psu.

What exactly does this last sentence mean? You're being
vague about the significant issues.

Am i pushing my luck with this? i cant find any power usage for scsi drives,
guess the latest ones use more power.

Worst-case scenario they shouldn't comsume more than 2.5A on
spin-up. If they aren't spinning up simultaneously you only
need allow an extra couple amps over typical consumption.
So determine if they all spin up at once and if so, allow
2.5V 12V per drive, else 1A per drive plus 2A. As for 5V
rail, 750mA per drive should be enough. Another issue is
how accurately the power supply is rated, if you only meet
bare minimum spec for drives but the power supply itself is
barely meeting IT'S spec, you're cutting more corners...
better to have too much capacity if that's manageable.

im not too up on scsi but learning, the scsi ng which i have used on and off
for a couple of years dont like question like this or not too great at
offering advice.

Also cooling advice would be great, a couple of brand websites offer temps
to be kept at but how do i check these? I keep them on 24/7 unless im
watching a dvd on the pc next to it as they are pretty loud.

ME and SE machines.

Actively cool the bays with the largest fan easily fit into
the chassis. Try to keep drives under 45C, but don't worry
too much if they're slightly higher, it's not like that's a
critical failure temp, just a range and it also depends
how/where you measured temp. Personally I like to keep
drives cool enough that side frame "feels" only mildly warm
if not cool.

 

[Julian Hales]

What exactly does this last sentence mean? You're being
vague about the significant issues.

one pc as normal with scsi card but all the drives are mounted in another
tower with its own psu

Worst-case scenario they shouldn't comsume more than 2.5A on
spin-up. If they aren't spinning up simultaneously you only
need allow an extra couple amps over typical consumption.
So determine if they all spin up at once and if so, allow
2.5V 12V per drive, else 1A per drive plus 2A. As for 5V
rail, 750mA per drive should be enough. Another issue is
how accurately the power supply is rated, if you only meet
bare minimum spec for drives but the power supply itself is
barely meeting IT'S spec, you're cutting more corners...
better to have too much capacity if that's manageable.

i was thining about Wattage output, say 4 drives via a 200w output. not sure
on rails etc

Actively cool the bays with the largest fan easily fit into
the chassis. Try to keep drives under 45C, but don't worry
too much if they're slightly higher, it's not like that's a
critical failure temp, just a range and it also depends
how/where you measured temp. Personally I like to keep
drives cool enough that side frame "feels" only mildly warm
if not cool.

2 of mine nearly burn me when i touch them, been liket that for years.
couldnt find software or how to acc measure them, one brand website said ok
to 5x? degree

I have a pile of no use cd roms and ide drives that i thought of slapping in
between for passivecooling.

 

[kony]

one pc as normal with scsi card but all the drives are mounted in another
tower with its own psu

Yes but, "its own psu" is not specific, it's vague. Your
quesiton is about specifics, so assessment of specifics,
requires specific info.

i was thining about Wattage output, say 4 drives via a 200w output. not sure
on rails etc

Wattage output not necessarily relevant, since it's the amps
per rail that matter and power supplies have been shifting
from more 5V to more 12V power. You don't really even need
an ATX power supply at all, nor an AT... Main thing is your
determination of how this external drive chassis is to be
turned on... how is this implemented on the other chassis,
and is that method how you'll want it implemented again?

To generalize, yes the typical, accurately rated 200W AT or
ATX power supply is enough for your described combination of
drives. You might use a multimeter to measure voltages
under peak loads, as many drives spinning, being accessed as
would ever happen simultaneously, and how long it takes 12V
rail to recover upon initial power-on of the unit.

2 of mine nearly burn me when i touch them, been liket that for years.
couldnt find software or how to acc measure them, one brand website said ok
to 5x? degree

That's far too hot for optimal lifespan, you're lucky that
they've lasted so long. It is generally not a good idea to
take the approach of merely keeping drives below the maximum
threshold, ideally a drive should be cool enough you could
leave your hand on it indefinitely. If you're content with
current situation it's your call but i'd do something about
that, it's generally not too hard to get drives down below
40C.

I have a pile of no use cd roms and ide drives that i thought of slapping in
between for passivecooling.

Is there really a benefit to using all those old drives? A
single semi-modern drive will have much higher capacity and
performance, not to mention higher expected reliability, use
less power, less noise, no need for another drive tower and
any of these issues being considered.

 

[Julian Hales]

Yes but, "its own psu" is not specific, it's vague. Your
quesiton is about specifics, so assessment of specifics,
requires specific info.

All i can see on the scsi powering psu is.

5v + 1A min 20A max
5v- 0 0.5
12v+ 0.4 8
12v- 0 .5

Guess its around 200W


they spin up at differant times. having dyslexia meant learning about scsi
and linux wasnt easy, a case of trial and error to im not too good on
terminolgy etc

Wattage output not necessarily relevant, since it's the amps
per rail that matter and power supplies have been shifting
from more 5V to more 12V power. You don't really even need
an ATX power supply at all, nor an AT... Main thing is your
determination of how this external drive chassis is to be
turned on... how is this implemented on the other chassis,
and is that method how you'll want it implemented again?

I belive AT, mounted in case and switch is earthed.

The other case i thought of using for the sca drives would be AT, in the
desktop case, due to the fact the compaq PSU's are not standard size and
wont fit in my towers.

To generalize, yes the typical, accurately rated 200W AT or
ATX power supply is enough for your described combination of
drives. You might use a multimeter to measure voltages
under peak loads, as many drives spinning, being accessed as
would ever happen simultaneously, and how long it takes 12V
rail to recover upon initial power-on of the unit.




That's far too hot for optimal lifespan, you're lucky that
they've lasted so long. It is generally not a good idea to
take the approach of merely keeping drives below the maximum
threshold, ideally a drive should be cool enough you could
leave your hand on it indefinitely. If you're content with
current situation it's your call but i'd do something about
that, it's generally not too hard to get drives down below
40C.

how can i measure a acc temp?

Is there really a benefit to using all those old drives? A
single semi-modern drive will have much higher capacity and
performance, not to mention higher expected reliability, use
less power, less noise, no need for another drive tower and
any of these issues being considered.

I dont like throwing things away and try to find a use for them. the 4
drives each hold data for my lan and 2 of them have important back up data
for the drivers for about 10 pc's. I often shift data over my lan.

Having one hd fail in 5 years, a ide minutes prior to backing up (pre cdrw
and network) i now keep data backed up on 2 drives, so orig hd and 2 others.

I often fix pc's so the scsi machine keeps all useful programmes and has its
uses. I know it old tech, noisy and not the fastest, but i love it. i drive
a rare 1977 Car, gives me more pleasure than any modern car i have drivern.
it needs respect and care. Plus i like to knock things up from other
peoples left overs.

Had you been in the UK, 2 weeks time im on a tv show for all the junk and
computers i knock up.

 

[kony]

All i can see on the scsi powering psu is.

5v + 1A min 20A max
5v- 0 0.5
12v+ 0.4 8
12v- 0 .5

Guess its around 200W

That's a ballpark, whichever PSU you choose might have
similar minimum amperage on each rail, some smaller ~ 200W
PSU of yesteryear might've had fewer 12V amps than above.

I belive AT, mounted in case and switch is earthed.

The other case i thought of using for the sca drives would be AT, in the
desktop case, due to the fact the compaq PSU's are not standard size and
wont fit in my towers.

With that kind of arrangement it could even use a non-"PC"
power supply, any typical switching power supply in that
amperage range is likely to have good enough specs, but of
course it'd be yet another thing to confirm if a non-PC PSU
were used instead.

how can i measure a acc temp?

You might google search for HDD temp utilities, though I
don't know if older SCSI drives would be supported.
Otherwise there's an infrared thermometer or more
traditional probe-on-wire type.

 

[Julian Hales]

That's a ballpark, whichever PSU you choose might have
similar minimum amperage on each rail, some smaller ~ 200W
PSU of yesteryear might've had fewer 12V amps than above.

its amazing what info mation i can find if i stand up and take a closer look

With that kind of arrangement it could even use a non-"PC"
power supply, any typical switching power supply in that
amperage range is likely to have good enough specs, but of
course it'd be yet another thing to confirm if a non-PC PSU
were used instead.




You might google search for HDD temp utilities, though I
don't know if older SCSI drives would be supported.
Otherwise there's an infrared thermometer or more
traditional probe-on-wire type.

I wasnt sure if the int or ext part of the drive was measured for temp, i
thought some software would read it, but i didnt think it could be accurate.
i installed Fresh diagnose and UI from from Fresh devices and ran sone
checks on the ide and scsi drives, the results were poor from that, yet some
maths, which im good at, just not english, on actual data speed transfer
knowing what the makers of the scsi card and drives stated showed the
software to be flawed. yes not the latest scsi hardware, but i havent got a
bottle neck etc.

checking google as i speak

thanks