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 Post subject: Hard drive power usage.
PostPosted: Thu Oct 23, 2008 3:14 am 
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I've got a little server in the attic doing router, firewall, file serving type duties. Currently has two Seagate ST3250623A-RK Barracuda drives mirrored. I was interested in what power consumption they have, from the Seagate stats page all that can be gleaned is: "Maximum start current, DC 2.80 amps". So if my basic physics memory serve me correctly, that's a max of 33.6W per drive (I presume they're on 12V yes). Quite a lot really, but that doesn't give a real world indication for general read/write/idle usage. I don't fancy pulling a drive out of the raid and measuring watts, too much hassle. Is there any other stats about I could consult?

Obviously I could swap in a couple of laptop drives, the Western Digital Scorpio in my desktop comes in with a max of 3W, but its gonna be money and hassle to swap to a pair of them. :( So I'll probably look more into getting Linux to hit the disks less often, less regular log file updates, /tmp in a ramdisk, etc...

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PostPosted: Thu Oct 23, 2008 6:51 am 
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Quote:
that's a max of 33.6W per drive (I presume they're on 12V yes).


They wont be anywhere near that, the wort tests I have seen for a drive at startup is 18W, usually they are at most 14W and many now are around 9-11W, at idle they vary from 6W to 9W.

They use 12v and 5v, 12v for the motor and 5v for the electronics (mostly). All 2.5" laptop drives BTW are 5v only.


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PostPosted: Thu Oct 23, 2008 10:44 am 
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andyb wrote:
All 2.5" laptop drives BTW are 5v only.

Do you have an idea of actual spin-up current required for notebook drives? I assume they also consume more power during start-up than when they're actually in use, right?


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 Post subject:
PostPosted: Thu Oct 23, 2008 2:06 pm 
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ST3250623A-RK
Power Management (watts)
Seek : 12.4
Read/Write : 12.8
Idle : 7.2
Standby : 1.4

Max power is much higher than power after spinup to nominal RPMs. It won't use that max power for even a quarter of a second.

the image below is from a seagate document about a server class scsi hard drive but the image conveys an important concept or two.
Image

Note the power spike is almost totally gone well before the drive is considered fully "ready" for normal use stats. The drive will attempt to execute commands asap, they just don't guarantee it will do so in x seconds.

for comparison 640GB modern drives from WD

Code:
640GB            Black   Blue   Green
Drive Ready Time 11 sec  13     14.3
R/W Power watts  8.3     8.3    5.4
Idle Power watts 7.7     7.7    2.5
Standby watts    1       1      0.46
Sleep            1       1      0.46


There is no reason to go to laptop drives with the Greenpower drives having so much better price per GB and still being low power and reasonably quiet.

But hey really the Seagates you have aren't that terribly bad in the power department if they are reading or writing. It's only the idle power draw that a "green" drive really shines vs the old drives you have.

http://www.silentpcreview.com/forums/vi ... ht=#435261 has the full post on those 640GB drives.

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PostPosted: Wed Oct 29, 2008 4:00 am 
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Fair enough, that doesn't seem so bad as I first suspected. Yeah don't think I'll be replacing the drives specifically to save power, just doesn't make sense.

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PostPosted: Wed Oct 29, 2008 12:20 pm 
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ilovejedd wrote:
Do you have an idea of actual spin-up current required for notebook drives? I assume they also consume more power during start-up than when they're actually in use, right?

Not sure. Its considerably lower than even the best 3.5" drives though, and normal 2.5" drives can be powered via USB which is handy for external drives.

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