Hacker News Reader

Comment by hosteur | Hacker News Reader

Getting 7200 rpm drives when expecting 5400 rpm drives may result in increased power consumtion and heat issues. Pluse 7200 rpm drives are noticably more noisy than 5400 rpm drives.

Many EMAZ and EZAZ seems to be affected.

It seems that the iOS app Phyphox can be used to determine if your drive is running at 7200 rpm or 5400 rpm using acoustic analysis.

From the comments:

> "There is an app called phyphox that allows you to access all of your phone's sensors. If you download it and use the Acceleration spectrum feature, you can measure the speed of your drive by simply placing your phone on top of the drive. The application is surprisingly accurate and I use it to check the health of my drives."

View on HN

For what it's worth, phyphox also has an android app. It's pretty good; my favorite app to play with on a flight

The data from this tool is fascinating! When you run the Acceleration Spectrum experiment there's a history view that makes a 120hz vibration extremely trivial to see.

You could just use a microphone and record it’s sound. You will see different frequency modes depending on the RPM.

> You could just use a microphone and record it’s sound. You will see different frequency modes depending on the RPM.

Yes, I believe this is what Phyphox does for you.

Most people have a microphone in their smartphone. But of course you could use a dedicated microphone and do a frequency analysis yourself instead.

Hmm, that app actually is pretty neat. It's published (for free, and under GPL) by the University of Aachen to support physics experiments. Recommended, at least from what I've seen so far.

This is true. Sometimes a 5400 rpm drive is desired.

If my memory serves me right, 7200 rpm result in higher spinning but reduced seeking/head noise (which I personally dislike more).

edit: I'm probably wrong

7200 RPM drives indeed have faster access (in terms of seek latency) and higher sustained throughput but, heat and power is not simple variables as one might think.

Especially RED drives are marketed for NAS systems (from home to SMB size). When a drives are installed into a closure, things like power and thermal budget comes into play.

NAS boxes are designed with strict limits and if they cannot cool themselves (and the drives) off or cannot supply the required power to drives; data corruption, performance/life span degradation may occur.

In extreme cases (with large storage arrays) calculated overall power budget can skew and may cause blackouts in some parts of the data center. There's a presumed ~2W difference in power consumption between 5.4K and 7.2K drives. We can safely install 60 of them in a 4U enclosure today. If we add 4 enclosures to a rack, that creates a ~480W difference, which is a one HPC server or 2-3 low-load, 1U or 2U servers. This is indeed significant.

While some of these drives are in MyBook enclosures, REDs may end up in very different places and may cause problems. In that case, head or spindle noise is not even the smallest concern.

If we're talking about noise, continuous (spindle) noise is much more degrading than head/seek noise. For me, even benign noises like USB fans have much more noticable effects after the day than mechanical keyboard noise for example.

> There's a presumed ~2W difference in power consumption between 5.4K and 7.2K drives.

Is that purely extra friction due to higher speed? Or is it spin up from sleep needing more power?

If we consider WD80EFAX [0], which is one of the suspect drives, that figure is for idle power consumption where disk is spinning but heads are not doing anything.

So, that difference is for sustaining higher spindle speeds.

The peak power requirement is 1.79A (~21.5W) which is probably consumed when starting from full-stop state (stand-by, sleep or power-off where motor is turned off).

[0]: https://media.flixcar.com/f360cdn/Western_Digital-3805661149...

[0]: https://products.wdc.com/library/SpecSheet/ENG/2879-800002.p...

Why would rotation speed inversely affect head noise?

Ever drive a manual transmission? At very low RPM the engine will seem to shake more. It isn't so much that there is less vibration at higher speeds but that it occurs at a higher frequency. That means the amount the part physically moves from one side of the oscillation to another is less, just as a higher-revving engine doesn't bounce around as much as it would at lower RPM. The total amount of noise/vibration may be similar but the change in frequency can still have other effects.

Yeah, I came to the same conclusion after thinking about it some more. Looks like a faulty memory.

> phyphox

Well, there goes my productivity for the day.

(edit: fixed typo)

I’ve tried the app approach, but I don’t know how to interpret the data. Can someone lend a hand?

Reply on news.ycombinator.com