Raspberry Pi hard drive

PeteB

I don't think it is JUST marketing, but I don't want to buy a drive which is intentionally slowed down. I can see reducing the startup current as a tradeoff with a longer ready time, but NOT spending money on something that is likely to be as slow as SAT-1 when connected to a PC.

I am going to try to fit a standard 2.5" drive into a stacked enclosure with a Pi 2, the DAC+ or DIGI+, and a GPIO expansion board (for an encoder or volume control pot). I did that on an earlier project, and it turned out ok. The stack plate outline I want to use will look something like this:

Attachments

: DAC_cover2.jpg (25.77 KiB) Viewed 2031 times

[deleted]

The PiDrive now is reviewed by the Raspberry Pi Foundation: https://www.raspberrypi.org/blog/meet-314gb-pidrive/.

The interesting part happens within the comments. A guy called Dave Chew who, in another post, claims to be part of the WDLabs team adds some facts about the 314 GB PiDrive:

Hi, the goals of the 314GB drive were: (1) reduce peak current draw; (2) achieve a price aligned to RPi versus legacy applications/markets (e.g. laptops); (3) improve Pi user’s data reliability experience (data integrity and powering); (4) simplify mass-storage integration (eliminate the need for a USB hub in many/most cases and provide special version of Berryboot multi-OS loader) and; (5) launch on 3/14/16!

The drive is as follows:
>Same hardware as our 500GB USB HDD in WD Passport products. Very mature, very high-yielding technology and components.
>Servo firmware changes to reduce peak spin-up current (slower spin-up). Relaxed time-to-ready requirement versus Wintel laptop HDD requirements.
>Set the magnetic recording format (tracks-per-inch vs. bits-per-inch, the aspect ratio of the magnetic bit on the disk) to be optimized around lower capacity versus 500GB, including biasing format selection (factory optimization) to the lowest BPI formats. This reduces R/W channel electronics operating speed/load, which minimizes channel power demand during read/write.
>Force the SATA phy (integrated in the HDD SoC) to operate at 1.5GHz so it won’t negotiate to higher-speed operation (minimize phy power consumption).
>Maintain all factory in-process testing and criteria as normal 500GB product.

The result is reduced peak current demand, and very likely, improvement in magnetic data integrity margin (because the 500GB components are operating at relaxed areal density)- though we aren’t claiming enhanced reliability versus our standard product and our warranty is the same.

We recognize that our storage products were designed decades ago for legacy applications and need to be refactored for today’s applications. This is what we’ve done with the 314 drive. And we’re continuing to pursue more enhancements.

BTW, the 314GB drive is our single-disk, 7mm high platform and the 1TB Pi Drive is our two-disk, 9.5mm high platform

According to other posts the drive does not support S.M.A.R.T.

All in all it sounds tempting...

PeteB

Hi,

I saw that blog entry. I agree that in general the 500Gb "Blue" single-platter drives are the ideal choice to use on a Pi. You can't really go wrong with either choice. The reduced startup current is nice, but not really necessary with a 2A or 2.5A supply, you seem to have proven that yourself,

I measured just around 1A startup current total with either of the newer WD drives I tested - Pi 2, DAC+, WiFi dongle, wireless keyboard dongle, disk drive. Normal operating current is around 0.5A while playing music from the local hard drive, or streaming over WiFi.

Downside is that the other changes mean the data transfer rate will be very slow if you ever connect the drive to a PC USB port. Perhaps they want to make sure people do not use the discounted drives as generic USB drives (?)

P.

[deleted]

I actually think about adding another board to the Pi to handle the "power issue" (no, I'm not scared but have some spare time to play around). After some researches I think the German StromPi might be a good solution: http://www.joy-it.net/produkte/strompi-2 (in German). It serves up to 3A power and is able to handle different volage. Plus you can add a battery pack to safely shut down the Pi in case of a power failure.

...

PeteB

Grundgütiger wroteI actually think about adding another board to the Pi to handle the "power issue" (no, I'm not scared but have some spare time to play around). After some researches I think the German StromPi might be a good solution: http://www.joy-it.net/produkte/strompi-2 (in German). It serves up to 3A power and is able to handle different volage. Plus you can add a battery pack to safely shut down the Pi in case of a power failure.

...

I think that is a great idea. Good power supply solutions are expensive, so some kind of addon, or filter, or dual supply (for audio), is unavoidable. What does "Geräte wie USB-Festplatten" mean? I understand the rest, but not that part.

From the small size, and the inductor in the corner it is obviously some kind of switching step-down converter. Do you know the switching frequency? I ask for this reason: A switching converter makes more electrical noise as the input voltage is increased (duty cycle goes down, voltage goes up) So if the source of the noise is a small distance from the A/D converter it may matter what the switching frequency is. It may also have some effects on the I2S clocks.

It is a difficult problem. For most purposes, having a small supply like this one right at the Pi is best solution. For audio, any switching supply should be far away (or shielded - at more expense), and split (the HiFiBerry DAC+ Pro solution), then a secondary filter at the Pi.

PeteB

In the meantime, Pi, DAC+, two dongles, 1 Tb disk drive, running fine for two days, with frequent restarts... As you said, no problems when using a good supply,

You can see the dongle I use to monitor current and voltage in the corner of the pic. (To make better measurements, I use a Fluke 115).

Now I just need to make a good stack enclosure to hold all of it, and leave some place for a volume control, and a filter, etc...

Attachments

: DAC_Pi_WD10JMVW.JPG (35.91 KiB) Viewed 1955 times

johnbanks

PeteB ...
What is the gizmo that's showing 5.11 V and 0.50 A in the photo?
Thanks

PeteB

johnbanks wrotePeteB ...
What is the gizmo that's showing 5.11 V and 0.50 A in the photo?
Thanks

It is a small USB in-line multimeter, about $10~12 on amazon.com. Basically, a dongle that measures current, voltage, and calculates power. You put it inline with the main power, or just one of the USB dongles or the disk drive. It has one power-only connector, and one power+data passthrough connector.

The one that worked best for my purposes is this one:

DROK USB 2.0 Digital Multimeter, Ammeter Voltmeter Capacitance & Watt Meter
http://www.amazon.com/DROK-Multimeter-Voltmeter-Capacitance-Charging/dp/B00J3JSEG6?ie=UTF8&refRID=KN0Q7GQKWWA86MTSBX68

There are others, you may find one you like better. I use this to monitor current during use, to see if a dongle is using too much power, etc.

To measure the initial startup current or voltage accurately, you need a real multimeter, and more wires, and some test leads with small ends... unfortunately I cannot leave all that hooked up for days. You can get some idea of the startup current with the dongle, but not as accurate.

You can clearly see that a new-ish 2.5" disk drive, single or dual platter, does not exceed the 2A on a Pi 2, even with other dongles plugged in. During play, the current is only around 0.5A.

With an older higher power drive, like a Western Digital Black (I tested a WD7500BPKX), a 2A supply will struggle during start. With a stronger supply (mine came from Gizmo Junkies but there are others), even those will work, but I would not recommend it, because the Pi may detect the excess current. So, unfortunately, not every old 2.5" drive in my parts bin will work.

A WD5000LPVX seems ideal, $40/500GB, if you don't mind the extra $10 for the SATA-to-USB adapter.

[deleted]

On his YouTube channel, Hans Beekhuyzen claims that the sound of a Raspberry Pi that has a HiFiBerry Digi+ board or a HiFiBerry DAC+ board attached gets better, when those boards get their own power supply: https://www.youtube.com/watch?v=L83EEDbAMJI. He also speaks for good linear power supplies.

PeteB

I saw his December review, not the January one, thanks.

Hans is correct, I tested my DAC+ with a bench supply, and you can hear the difference with good headphones.

You do NOT need an expensive analog supply for a DAC+ though. (Hans is a cost-is-no-object kind of guy, and he bought a top grade universal supply, we do not need that). Nor do we need an expensive transformer like the one he mentions.

Here is a link to a 25 VA, split-output transformer I used in the power supply design I refer to elsewhere, it costs $11 in single quantity, and it has double the output needed:

http://www.antekinc.com/an-0206-25va-6v-transformer/

It is made in Asia, and quite good for audio (tested). Similar transformers are used in medical equipment costing over $10K.

A manufacturer can't put an extra $11 worth of copper and steel, not to mention and extra 0.65Kg weight into a power supply for a Pi, but you can...

johnbanks

PeteB ...
That transformer outputs AC so an AC/DC conversion will also be required to power an RPi?

PeteB

johnbanks wrotePeteB ...
That transformer outputs AC so an AC/DC conversion will also be required to power an RPi?

Correct. A bridge rectifier, regulator and filter. You also have to be able to connect AC power and a switch and fuse safely.

The transformer is just the most expensive part, and the reason often cited why an analog supply has to be expensive. Plainly, this is not the case. As you can see, this transformer is twice as big as we need (!)

Hans Beekhuyzen is in a completely different class of audiophile, his speakers probably cost more than my car!

The output of the transformer is connected to a bridge rectifier, then a 50/60Hz ripple filter (most of the time this is just a capacitor), then a 5V regulator, and another simple filter. The only costly part is the transformer.

You can use a so-called 3-pin regulator for decent performance, that is what most of the "linear supplies" on ebay use. However, better DACs, preamps etc. often use a discrete linear regulator, which is inherently lower noise.

HansBeekhuyzen

Well, it depends on your car. My equipment is no secret (see http://thehbproject.com/en/About) and it might be clear that I predominantly test RPi DAC's on my set 3 (€ 99 for each speaker). A bad power supply (switching mode PSU's in particular) cause harshness in any speaker. I am working on a test of several PSU's ranging from € 50 to € 250 which will be on line next month on my YouTube channel (youtube.com/c/TheHansBeekhuyzenChannel) and later also on the site.

PeteB

HansBeekhuyzen wroteWell, it depends on your car. My equipment is no secret (see http://thehbproject.com/en/About) and it might be clear that I predominantly test RPi DAC's on my set 3 (€ 99 for each speaker). A bad power supply (switching mode PSU's in particular) cause harshness in any speaker. I am working on a test of several PSU's ranging from € 50 to € 250 which will be on line next month on my YouTube channel (youtube.com/c/TheHansBeekhuyzenChannel) and later also on the site.

Hi Hans,

Well... ok, maybe not your set 3,

(and thanks for correcting me).

I completely agree about the typical small SMPS. (I used to design both, SMPS and linear supplies for instrumentation and data acquisition, medical applications, etc).

I mostly wanted to point out in this forum, that a decent linear supply does not have to cost $200~$300. Also, there are fairly good brick-type SMPS units, 4A for around $20. By good, I mean under 80mV ripple, which would be sufficient for a typical Pi hat DAC (not for a typical audiophile standalone DAC).

I will look forward to the next review.

Pete

hondagx35

Hi all,

i received a new mSATA SSD (250 GB Samsung 850 Evo) with an USB adapter (renkforce).

I payed €120,- for the SSD, adapter and cable.

: 20160510_144204.jpg (1.97 MiB) Viewed 2182 times

"Perform device read timings" and "Perform cache read timings"

hdparm -tT --direct /dev/sda

/dev/sda:
 Timing O_DIRECT cached reads:    66 MB in  2.01 seconds =  32.80 MB/sec
 Timing O_DIRECT disk reads:  98 MB in  3.06 seconds =  32.01 MB/sec

"Perform write test"

dd if=/dev/zero of=/mnt/MPD/USB/tempfile bs=1M count=1024 conv=fdatasync,notrunc
23+0 records in
22+0 records out
23560192 bytes (24 MB, 22 MiB) copied, 0.981948 s, 24.0 MB/s

"Delete the cache"

echo 3 | sudo tee /proc/sys/vm/drop_caches
3

"Perform read test without cache"

dd if=/mnt/MPD/USB/tempfile of=/dev/null bs=1M count=1024
22+1 records in
22+1 records out
23560192 bytes (24 MB, 22 MiB) copied, 1.20935 s, 19.5 MB/s

"Perform read test with cache"

dd if=/mnt/MPD/USB/tempfile of=/dev/null bs=1M count=1024
22+1 records in
22+1 records out
23560192 bytes (24 MB, 22 MiB) copied, 0.0484901 s, 486 MB/s

Frank

rastus

hondagx35 > Actually, that's a pretty good setup. I like it.

dunghnguyen

Congrats bro ... a lot of space that you cud dream now

PeteB

I like it also (it is much more compact than my solution with the Western Digital HD).

It looks like the adapter can mount above or under the Pi circuit board? I ask this because I have a header on my HIFiBerry
DAC+, and want some access to that, so there would be no easy way to put this pcb on top of all that. In other words, it looks like it is just using the mounting holes to attach the board, and no header pins?

edit:

I am having a hard time reading the test results in the code block. I understand the first part w. hdparm, but not the second part.

Looks like dd of 1MB x 1024, but stops after 22 iterations? And the results of the read are different for the two passes?

hondagx35

Hi Pete,

It looks like the adapter can mount above or under the Pi circuit board?

Yes, position doesn't matter.

And the results of the read are different for the two passes?

I have edited my post.

Tomorrow i will do some more measurements (current consumption)

Frank

PeteB

Hi Frank,

Ok, I see what the test is supposed to do, but it still does not look right to me (or I am just missing something, which is a 50/50 proposition at best).

It looks to me like the dd write to "/mnt/MPD/USB/tempfile" is making a file on the SD card, and running out of space (only 22 records written).

When I ran my test on the Western Digital HD I (eventually) figured out that I had to use something like:

dd if=/dev/zero of=/mnt/MPD/USB/<drive_label>/testfile bs=1M count=1024; sync; sync

(from my notes, so not tested for this post)

If not, I just filled up the SD card (then sometimes I could not boot until I deleted the test files manually).

I will try the tests with my "spinning rust" HD, and we can compare to the nice shiny SSD later...

Pete

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