Spin down harddrives. Worth it?

This is a discussion on Spin down harddrives. Worth it? within the Tech Board forums, part of the Community Boards category; Are people still spinning down their harddrives? I tried setting the harddrive in my laptop to spin down after 1 ...

  1. #1
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    Spin down harddrives. Worth it?

    Are people still spinning down their harddrives?

    I tried setting the harddrive in my laptop to spin down after 1 minute of inactivity, and noticed that the battery life has not lengthened significantly (didn't time it). I'm sure the drive was spun down, as I can hear the motor when it's running. When an application needs to access the harddrive when it's spun down, there's about a 3 seconds delay. Definitely noticeable. It needs to wake up once every few minutes, too, to commit the journal to disk.

    I looked up the specs of my drive -
    WD Scorpio Blue 320 GB SATA Hard Drives ( WD3200BEVT )

    and it says -
    Power Dissipation
    Read/Write 2.50 Watts
    Idle 0.85 Watts
    Standby 0.25 Watts
    Sleep 0.10 Watts
    (By the way, what's the difference between 5V DC and "power dissipation"? I have always thought P=IV, and it only doesn't agree for the "Idle" power)
    I'm assuming idle means still spinning, and standby means spun down.

    For 0.5W difference... I don't know. And then motors draw high currents spinning up, so there may be no power saving at all if spun up frequently enough! (just free lag)

    I was surprised that by default, Ubuntu doesn't spin down laptop harddrives on idle. I'm beginning to see why.

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    Is there a way to use a USB Flash Drive on Linux the same as the ReadyBoost feature of Vista?

    Edit: Oops, didn't even see your other post about ReadyBoost for Linux before replying.
    Last edited by cpjust; 06-07-2009 at 11:06 AM.
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    C++まいる!Cをこわせ! Elysia's Avatar
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    Yeah, P = UI (or P = VI for you US junkies, shame on you).
    I tend to not spin down the drives. It saves an insignificant amount of power for it to be worth it. It's annoying when it has to spin up again.

    I don't know why you think it doesn't seem to agree?
    If U = 5V, and it uses 2.5W, then it means it uses 0.5A. Or does it say differently somewhere?
    Quote Originally Posted by Adak View Post
    io.h certainly IS included in some modern compilers. It is no longer part of the standard for C, but it is nevertheless, included in the very latest Pelles C versions.
    Quote Originally Posted by Salem View Post
    You mean it's included as a crutch to help ancient programmers limp along without them having to relearn too much.

    Outside of your DOS world, your header file is meaningless.

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    Quote Originally Posted by Elysia View Post
    Yeah, P = UI (or P = VI for you US junkies, shame on you).
    I tend to not spin down the drives. It saves an insignificant amount of power for it to be worth it. It's annoying when it has to spin up again.

    I don't know why you think it doesn't seem to agree?
    If U = 5V, and it uses 2.5W, then it means it uses 0.5A. Or does it say differently somewhere?
    Interesting
    What does U stand for?

    In Canada, I learned it as: P = EI

    E = Electromotive Potential
    "I am probably the laziest programmer on the planet, a fact with which anyone who has ever seen my code will agree." - esbo, 11/15/2008

    "the internet is a scary place to be thats why i dont use it much." - billet, 03/17/2010

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    C++まいる!Cをこわせ! Elysia's Avatar
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    U stands for voltage. The standard letter (except for USA who uses V).
    I suspect you are talking about the voltage you get from a battery whose term I cannot name in english. It is not different from U except the the voltage from a battery will drop as the load increases.
    But, generally, in your normal formula collection, it is named as P = UI. A battery is often seen as a voltage source and a resistor connected serially.
    Well, doesn't matter much in this case since the voltage should be constant.
    Last edited by Elysia; 06-07-2009 at 03:04 PM.
    Quote Originally Posted by Adak View Post
    io.h certainly IS included in some modern compilers. It is no longer part of the standard for C, but it is nevertheless, included in the very latest Pelles C versions.
    Quote Originally Posted by Salem View Post
    You mean it's included as a crutch to help ancient programmers limp along without them having to relearn too much.

    Outside of your DOS world, your header file is meaningless.

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    Super Moderator VirtualAce's Avatar
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    Is your power bill high or something? Spinning down your drives is insignificant in savings but far more significant when a program needs to use the drive. It can cause serious lag in games for sure and sometimes if the data is time critical it can cause apps to crash if they do not handle the situation correctly.

  7. #7
    pwns nooblars
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    Bubba: Most of these discussions for things like spin downs are about laptops and typically not about desktops. (Though for home server usages there is talk of power concerns due to 100% desired uptime)

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    Super Moderator VirtualAce's Avatar
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    It is still a moot point.

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    Yeah, it's about laptops. I heard it's really bad for desktops, since desktop drives are designed to take a lot less load cycles (or whatever they call it, spinning up and down) before they fail.

    I have not noticed any crashing on my Linux laptop (set it to spin down for a few days).

    And I learned it as P = VI. I'm in Canada. We use Emf, electromotive force (a misnomer, since it's not a force), too, for voltage sources (at no load, so no voltage drop due to internal resistance). For voltage drops across other circuit elements, we use V.

    On the page, it says, for idle, 400mA and 0.85 Watts (5V). It matches for all other 3 (active, standby, sleep). Perhaps the current is maximum current? (Idle can include spinning up)

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    Quote Originally Posted by cyberfish View Post
    And I learned it as P = VI. I'm in Canada. We use Emf, electromotive force (a misnomer, since it's not a force), too, for voltage sources (at no load, so no voltage drop due to internal resistance). For voltage drops across other circuit elements, we use V.
    In my high school electronics class we used V when listing the number of volts & A when listing the number of amps, but E & I in formulas for some reason. This was in the early 90's, so maybe the textbooks changed?
    "I am probably the laziest programmer on the planet, a fact with which anyone who has ever seen my code will agree." - esbo, 11/15/2008

    "the internet is a scary place to be thats why i dont use it much." - billet, 03/17/2010

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    We use V and A for units, V and I for constant voltages and currents, v and i (lowercase) for time-varying voltages and currents (first year university physics).

    Maybe they use different things on the east coast (French influence?)

  12. #12
    Woof, woof! zacs7's Avatar
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    Not to mention it decreases the life of the drive, especially when the heads park.

    The 120GB WD scorpio in my laptop parks the heads / spins down about every 10 seconds. The clicking noise is rather annoying. And it reduces the life of the drive significantly, I know it's supposed to increase the life if I dropped it, but I don't :-). So off it went.

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    Captain Crash brewbuck's Avatar
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    Quote Originally Posted by Elysia View Post
    U stands for voltage. The standard letter (except for USA who uses V).
    I suspect you are talking about the voltage you get from a battery whose term I cannot name in english. It is not different from U except the the voltage from a battery will drop as the load increases.
    U, in any equation I've ever seen, means potential energy (units == joule). Something which voltage decidedly is not.

    EDIT: The P=I*V equation is only true instantaneously. For time-varying potentials or currents, the relationship must be treated as a differential one, and integrated over time.
    Code:
    //try
    //{
    	if (a) do { f( b); } while(1);
    	else   do { f(!b); } while(1);
    //}

  14. #14
    C++まいる!Cをこわせ! Elysia's Avatar
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    U is the standard symbol for voltage. I don't remember if it's IEC (or whatever it's called) or simply European. But USA lists is as V, for some stupid reason.
    And energy? If I remember correctly from the physics, it's unit (?) is W.
    Although I haven't heard about current, we do use small u for a voltage that is not constant, such as a voltage you could measure at a certain point in time from an AC source, say.
    Still, when doing calculations, it is usually converted to a constant voltage first (U).

    And we must remember to separate the formulas and units (or whatever it's called in english).
    We measure current in ampere, A for short, but it's written as I on formulas.
    Likewise, we measure voltage in volts, V for short, but it's written as U on formulas (in Europe, at least; though not US).
    These Emf formulas are mostly physics. In electronics, I haven't seen them used at all. Slightly similar formulas in magnetic fields, but not electronics... it's all about voltage (U/V), current (I) and wattage (P).
    Quote Originally Posted by Adak View Post
    io.h certainly IS included in some modern compilers. It is no longer part of the standard for C, but it is nevertheless, included in the very latest Pelles C versions.
    Quote Originally Posted by Salem View Post
    You mean it's included as a crutch to help ancient programmers limp along without them having to relearn too much.

    Outside of your DOS world, your header file is meaningless.

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    Well, SI uses V. Wikipedia page has no mention of "U", either.

    U usually represents potential energy (unit J), and voltage the potential energy per unit charge (V = J/C), so you might have them confused.

    Watts is a unit of power (rate of energy transfer, J/s).

    Energy is measured in joules.

    All these are SI (Système International) units. AFAIK, they are used by everyone EXCEPT pretty much the US (they still use imperial units - pounds, slugs, miles, yards...).
    http://en.wikipedia.org/wiki/SI

    You are right that most quantities have different abbreviations than their standard units, but voltage is an exception. Maybe at whereever you live, they changed it to U to disambiguate it? AFAIK, that's not a standard practice, though. Understandable, however, just like how electrical engineers use j for the imaginary unit (instead of i) since i is usually used for current in that context.

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