What contributes more to hard drive heat production?

[Gunbuster]

I was talking with a friend about hard drives and we got to wondering. What contributes more to the drive temperature? Is it the spindle motor or friction from platter to air interface that creates most of the heat in a traditional hard drive?

 

[C1]

A guess is that air friction is a minor contributor to energy consumption. What Ive noticed (and you can demonstrate to yourself) is that writing to a drive noticeably results in heating.

Take a look at some energy consumption specs:
http://www.wdc.com/wdproducts/library/SpecSheet/ENG/2879-701229.pdf

What is evident is that most power is used for the spindle. However, as the drive density increases, the relative contribution of heating from R/W is less.

In a small drive (like say a 320Gb), heating associated with writing is really really substantial. Try it once using touch/feel.

 

[PsiStar]

A result of the air interface is minimal friction. Therefore minimal heat generated.

If there really is a temperature increase during writing, then it must be the electronics necessary to generate the drive current to the drive head to write on the disk(s).

 

[C1]

A result of the air interface is minimal friction. Therefore minimal heat generated.

If there really is a temperature increase during writing, then it must be the electronics necessary to generate the drive current to the drive head to write on the disk(s).

Just a note to all. I was cautious about the effect of the friction. It is not the friction per se that generates any heat of concern, but drag on the spindle motor rotation. Remember from your physics class that electric motors are effectively a dead short when the armature is not spinning to generate "back emf". So drag on armature rotation is able to drastically increase the current thru the motor (resulting in subsequent heating - doesnt take much).

 

[Gunbuster]

Just a note to all. I was cautious about the effect of the friction. It is not the friction per se that generates any heat of concern, but drag on the spindle motor rotation. Remember from your physics class that electric motors are effectively a dead short when the armature is not spinning to generate "back emf". So drag on armature rotation is able to drastically increase the current thru the motor (resulting in subsequent heating - doesnt take much).

So more platters = more mass to spin = more heat generated by the spindle motor?

 

[C1]

More inertia to overcome (spin up and maintain), more surface area for drag (multi-platter) and more weight (and hence bearing friction) would make a multi-platter system more prone or vulnerable to energy consumption. If you were having an energy saving contest, all things being equal, which would you bet on - single platter or dual platter?

Now storage capacity (and maybe even reliability/complexity, noise/vibration), is another issue isnt it?

 

[bryanl]

An idea the power needed per extra platter can be found on page 18 of the Seagate documents for these Barracuda drives manufactured in both 2 and 3 platter versions, on page 18:

http://www.seagate.com/files/staticfiles/support/docs/manual/desktop/Barracuda 7200.14/100686584.pdf

   platters       idle        operating

        1         3.36W        5.90W
        2         4.50W        6.70W
        3         5.40W        8.00W

 

[ThePolarSky]

...

 

[sao123]

I thought hard drives were vacuum sealed to prevent even micron sized dust particles from scratching the surface?

My guess is most of the heat comes from the power required to run the motor. And the lack of airflow contributes to lack of internal cooling.

 

[C1]

I thought hard drives were vacuum sealed to prevent even micron sized dust particles from scratching the surface?

My guess is most of the heat comes from the power required to run the motor. And the lack of airflow contributes to lack of internal cooling.

Ya, right. Have you ever read the label on an HDD?
"Do not cover this hole?"
http://superuser.com/questions/368774/do-not-cover-this-hole

 

[atpokey]

passively cooled with minimal surface area allows minimal energy to cause a significant heating effect over ambient as well. It's not huge amounts of power that goes into HDs.