What's louder? Two 2-platter drives Or One 4-platter drive?

Silencing hard drives, optical drives and other storage devices

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Runes
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What's louder? Two 2-platter drives Or One 4-platter drive?

Post by Runes » Sat Aug 10, 2013 10:03 pm

Take for example, the new Seagate NAS series drives.

The 2TB uses two 1TB platters.
The 4TB uses four 1TB platters.
(the 3TB uses four 750GB platters though)

The 2TB drive is listed as
Idle
1.9 bels (typical)
2.0 bels (max)____
Seek
2.1 bels (typical)
2.2 bels (max)


And the 4TB as
Idle
2.3 bels (typical)
2.4 bels (max)____
Seek
2.5 bels (typical)
2.6 bels (max)

1 bel = 10 decibels. though dbA is weighted differently towards human hearing so it can't be directly compared to dbA. bels/decibels represents loudness across all frequencies.

Accoustically, how do HDDs compound eachother? :?:

I know sound pressure isn't absolute because human hearing is more sensitive to certain types of noise. Do multiple HDDs compound noise and make it worse, or is it similar to having multiple quiet fans being more soothing than one loud fan?

p.s. If this has been addressed somehere already I appologize. I did search but couldn't find anything.

Vicotnik
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Re: What's louder? Two 2-platter drives Or One 4-platter dr

Post by Vicotnik » Sun Aug 11, 2013 12:28 am

I would go for a single drive. I think it would be less noisy. But this depends much on application I think. Two poorly decoupled drives can cause a lot of noise, but you could also let one drive sleep.
For future upgrades I think you are better of with the bigger drive though. Also cost is a factor; I usually go with what gives most bytes for the buck.

mentawl
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Re: What's louder? Two 2-platter drives Or One 4-platter dr

Post by mentawl » Sun Aug 11, 2013 1:51 am

Personally, I notice the combi/destructive noises caused by two HDDs far more than I notice the noise of a single "loud" HDD. HDDs, even of an identical make, rarely spin at *exactly* the same rotational speed, so you can end up with some weird acoustics. More of a problem if you're hard mounting drives, as the case tends to amplify. Just my $0.02 :)

Runes
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Re: What's louder? Two 2-platter drives Or One 4-platter dr

Post by Runes » Thu Aug 15, 2013 1:34 pm

Vicotnik wrote:I would go for a single drive. I think it would be less noisy. But this depends much on application I think. Two poorly decoupled drives can cause a lot of noise, but you could also let one drive sleep.
For future upgrades I think you are better of with the bigger drive though. Also cost is a factor; I usually go with what gives most bytes for the buck.
Both drives are almost equal in $ per GB. Right now the 2TB is $110 (newegg/amazon) and the 4TB is $200 (NCIX/TigerDirect).

I'm not familiar with putting drives to sleep. I don't think these NAS drives are designed to sleep like the Green drives. I've read a little of the sleep thread on SPCR which involves doing it manually, but I'm not sure if that would be bad for them long term.

mentawl wrote:Personally, I notice the combi/destructive noises caused by two HDDs far more than I notice the noise of a single "loud" HDD. HDDs, even of an identical make, rarely spin at *exactly* the same rotational speed, so you can end up with some weird acoustics. More of a problem if you're hard mounting drives, as the case tends to amplify. Just my $0.02 :)
What if you mount the drives suspended? Do you think two drives that are 1/2 as lound as one drive would be quieter then?

The Seagate NAS drives are a nice example because they're exactly 3-4 db apart. and 3.something more db = 2x the loudness.

I'm also thinking that if you have 2x 2-platter drives. And you're accessing data off of one at a time, the other will be at idle.

So you have 19db idle + 21db seek

vs 25db seek (22db + 22db equiv)

But then like you said, they'd be at different speeds. I don't know if that would make more or less noise.

edh
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Re: What's louder? Two 2-platter drives Or One 4-platter dr

Post by edh » Fri Aug 16, 2013 12:21 am

A single drive is better. Think about it from this perspective: which uses more power? A 2 platter drive will use a little less than a 4 platter drive but not much less so doubling up 2 platter drives will use substantially more power than a single 4 platter drive. The noise from a hard disk comes from the mechanics of it and with a single drive you only have one mechanism, using less power and noise is simply one form of waste energy. If you waste more power from the same means, you'll naturally have more noise.

Runes
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Re: What's louder? Two 2-platter drives Or One 4-platter dr

Post by Runes » Sat Aug 17, 2013 4:59 am

edh wrote:A single drive is better. Think about it from this perspective: which uses more power? A 2 platter drive will use a little less than a 4 platter drive but not much less so doubling up 2 platter drives will use substantially more power than a single 4 platter drive. The noise from a hard disk comes from the mechanics of it and with a single drive you only have one mechanism, using less power and noise is simply one form of waste energy. If you waste more power from the same means, you'll naturally have more noise.
I can see that.

I understand the idea behind it, but I still wonder if it's actually true. Especially given the quoted sound pressure numbers.

e.g.
4-platter seeking
25db = (22db + 22db)

22db = (19db + 19db)

so 25db = (19db + 19db + 19db +19db)

vs. 2 2-platter drives

21db = (18db + 18db)

so with 2 2-platter drives. If one was seeking and one was idle
(18db + 18db + 19db)

If both were seeking (18db + 18db + 18db + 18db)

Idle
4-platter
23db = (20db + 20db)

2x 2-platter
19db + 19db



I wish someone would do a study on it. I almost want to buy 3 drives and try it myself. But all I have is an old radio shack sound meter which most likely isn't very accurate.

It seems incredibly close, to the point where the sound signature might be more important than the actual sound pressure.

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Re: What's louder? Two 2-platter drives Or One 4-platter dr

Post by Vicotnik » Sat Aug 17, 2013 6:08 am

Like you say, you need good equipment to test this. The whole thing is very academic if you ask me. If you care about noise so much that 1 vs 2 drives, number of platters the same, becomes interesting isn't a large SSD or NAS in another room more interesting still? :)

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