kuchenkruste
Posts: 9
Joined: Thu Jul 18, 2019 11:22 am

Raspberry Pi 4 & HDD

Thu Jul 18, 2019 11:52 am

Hey there,

I am currently trying to build a home server with the new Raspberry Pi 4 (incredible performance btw). So I bought this HPTC case Inter-Tech ITX-601 which provides an external power supply (60 W) and an internal atx interface (which I use as the power supply for the RPi, it should provide 5V @ max. 10A). I planned to attach two 2,5" WD HDDs via the Delock SATA to USB2.0 converter, which claims to need no additional drivers. The HDDs are connected to a separate power supply of the HPTC casing.

Unfortunately, the HDDs are not recognized by the RPi. The command

Code: Select all

lsblk
only lists the sd card. The command

Code: Select all

dmesg
prints the following (only one HDD is connected):

Code: Select all

[  158.812724] usb 1-1-port3: Cannot enable. Maybe the USB cable is bad?
[  158.912417] usb 1-1.3: new high-speed USB device number 13 using xhci_hcd
[  159.822650] usb 1-1-port3: Cannot enable. Maybe the USB cable is bad?
[  159.822928] usb 1-1-port3: attempt power cycle
[  161.072728] usb 1-1-port3: Cannot enable. Maybe the USB cable is bad?
[  161.982700] usb 1-1-port3: Cannot enable. Maybe the USB cable is bad?
[  161.982982] usb 1-1-port3: unable to enumerate USB device
During my own troubleshooting session I have tried different usb ports and states (HDD connected before/after booting e.g.). Only once, one HDD was recognized for a short period of time. I could not reproduce this since then. Any kind of help is very appreciated, especially as I am not a hardware expert.

Thank you very much for your time :-)

jamesh
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
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Re: Raspberry Pi 4 & HDD

Thu Jul 18, 2019 1:20 pm

Purely a guess, but it does sound power related, since I presume you have tried a different USB cable.
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kuchenkruste
Posts: 9
Joined: Thu Jul 18, 2019 11:22 am

Re: Raspberry Pi 4 & HDD

Thu Jul 18, 2019 9:01 pm

Thanks for your response! :D

As you presumed, I have already tried different USB cables. The outcome, however, remained the same.

I have already suspected the power supply but could not figure out why this could be a problem. Especially as I attached the ATX/SATA power cable to the HDDs, so that the RPi only needs to provide a small amount of power for the data cable.

In the meantime, I have tried to attach an external USB3.0 HDD, which worked flawlessly.

Do you have any suggestions how I can verify that the power is indeed the problem?

andrum99
Posts: 707
Joined: Fri Jul 20, 2012 2:41 pm

Re: Raspberry Pi 4 & HDD

Thu Jul 18, 2019 10:19 pm

kuchenkruste wrote:
Thu Jul 18, 2019 9:01 pm
Thanks for your response! :D

As you presumed, I have already tried different USB cables. The outcome, however, remained the same.

I have already suspected the power supply but could not figure out why this could be a problem. Especially as I attached the ATX/SATA power cable to the HDDs, so that the RPi only needs to provide a small amount of power for the data cable.

In the meantime, I have tried to attach an external USB3.0 HDD, which worked flawlessly.

Do you have any suggestions how I can verify that the power is indeed the problem?

Use an official Raspberry Pi power supply to power the Pi. Whatever the spec of your power supply says, the critical thing for the Pi is the voltage that it receives. Even if your Pi doesn't show the low voltage warning on the screen, this does not always mean the power supply is adequate.

carbone
Posts: 19
Joined: Tue Jul 16, 2019 6:09 pm
Location: Sheffield UK

Re: Raspberry Pi 4 & HDD

Thu Jul 18, 2019 10:55 pm

I think it is a power problem. You need to know the specification of the 5 volt rail. The 3.3 volt rail will probably be specced for most power. You can not just not connect to other rails and expect all power to be diverted to the 5 volt rail.

kuchenkruste
Posts: 9
Joined: Thu Jul 18, 2019 11:22 am

Re: Raspberry Pi 4 & HDD

Sat Jul 20, 2019 3:20 pm

I am sure by now, that you are right. After a few more experiments I was able to attach one of the HDDs. I tried yet another USB cable and it seems, that the previous cables had too much resistance (but that is just a guess of someone who has no idea about hardware :?).
Use an official Raspberry Pi power supply to power the Pi.
Although that is probably a working solution, I would like to use the built-in power supply of my casing. Don't get me wrong, I'll come back to your solution when there is no other way. But I would like to avoid buying a new power supply for now. :)
You need to know the specification of the 5 volt rail.
Unfortunately I have no "precise" specification - the only one I could find just contains the following information:
  • +3.30 V @ 10.0 A
  • +5.00 V @ 10.0 A
  • +5.00 VSB @ 2.0 A
  • +12.00 V @ 4.5 A
  • -12.00 V @ 0.15 A
As soon as I attach the second HDD both drives turn on and off alternately (lsblk prints either /dev/sda or /dev/sdb). Is there any way how I can get this running?

I have found a few blog posts where a PC power supply is used as power source for similar projects. One of those posts mentions, that a power supply like mine requires a minimum consumption. Shouldn't the RPi4 with two connected HDDs (each requires max. 800mA, but probably @ 12V) be sufficient enough to achieve such a minimum consumption?

Thanks for all your answers so far! I appreciate your help! :D

carbone
Posts: 19
Joined: Tue Jul 16, 2019 6:09 pm
Location: Sheffield UK

Re: Raspberry Pi 4 & HDD

Sat Jul 20, 2019 4:01 pm

If you add that up it is approx 145 W which you are trying to supply from a 60 W power source. So divide by 2.5 which will give 5 volts at 4 A assuming 100 % efficiency. ( probably more like 90% ) If you are connecting the drives to a Molex or SATA power connector on your power supply it will be internally connected to 5 V so your drives will take 1.6 A max. You need a bigger external power adaptor

fruitoftheloom
Posts: 20138
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Location: Delightful Dorset

Re: Raspberry Pi 4 & HDD

Sat Jul 20, 2019 4:04 pm

kuchenkruste wrote:
Sat Jul 20, 2019 3:20 pm
I am sure by now, that you are right. After a few more experiments I was able to attach one of the HDDs. I tried yet another USB cable and it seems, that the previous cables had too much resistance (but that is just a guess of someone who has no idea about hardware :?).
Use an official Raspberry Pi power supply to power the Pi.
Although that is probably a working solution, I would like to use the built-in power supply of my casing. Don't get me wrong, I'll come back to your solution when there is no other way. But I would like to avoid buying a new power supply for now. :)
You need to know the specification of the 5 volt rail.
Unfortunately I have no "precise" specification - the only one I could find just contains the following information:
  • +3.30 V @ 10.0 A
  • +5.00 V @ 10.0 A
  • +5.00 VSB @ 2.0 A
  • +12.00 V @ 4.5 A
  • -12.00 V @ 0.15 A
As soon as I attach the second HDD both drives turn on and off alternately (lsblk prints either /dev/sda or /dev/sdb). Is there any way how I can get this running?

I have found a few blog posts where a PC power supply is used as power source for similar projects. One of those posts mentions, that a power supply like mine requires a minimum consumption. Shouldn't the RPi4 with two connected HDDs (each requires max. 800mA, but probably @ 12V) be sufficient enough to achieve such a minimum consumption?

Thanks for all your answers so far! I appreciate your help! :D

The Raspberry Pi has a total of 1200mA available for the USB ports, there is no per port seperation, when using a quality power supply like the official one:

https://www.raspberrypi.org/documentati ... /#pi-power
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kuchenkruste
Posts: 9
Joined: Thu Jul 18, 2019 11:22 am

Re: Raspberry Pi 4 & HDD

Sat Jul 20, 2019 5:31 pm

If you add that up it is approx 145 W which you are trying to supply from a 60 W power source. So divide by 2.5 which will give 5 volts at 4 A assuming 100 % efficiency. ( probably more like 90% ) If you are connecting the drives to a Molex or SATA power connector on your power supply it will be internally connected to 5 V so your drives will take 1.6 A max. You need a bigger external power adaptor
That would explain my struggle with this setup - but how did you get to those numbers? The label of the HDDs indicates that they need 5V @ 0,8A (I just checked that). The datasheet, however, specifies them as 5V @ 1.1A (peak). So lets assume that they need 6W in the worst case. The RPi itself should need around 15W. So we end up with 2 * 6W + 15W = 27W which should be perfectly fine for a 60W power supply. Or did I forget something?
The Raspberry Pi has a total of 1200mA available for the USB ports, there is no per port seperation, when using a quality power supply like the official one:
I already knew that the RPi has a limit for its USB ports - that's why I bought internal 2.5" HDDs in the first place. My idea was to connect those HDDs to the ATX/SATA power connector of my power supply, so the RPi only has to bother with the current for the data cable (though I don't know how much power the data cable of a SATA device needs).

Thanks for your answers!

carbone
Posts: 19
Joined: Tue Jul 16, 2019 6:09 pm
Location: Sheffield UK

Re: Raspberry Pi 4 & HDD

Sat Jul 20, 2019 6:13 pm

You do not have 5 independent power supplies. All the voltage rails are linked and the design dictates the amount of power available to each voltage rail. You can not divert power to one rail by leaving the others unused. The only way is to provide more power from the external power supply. 150 W at least for the max ratings of the power supply you quote, although 120W should be more than adequate for the set up you quote unless you start making additions.

kuchenkruste
Posts: 9
Joined: Thu Jul 18, 2019 11:22 am

Re: Raspberry Pi 4 & HDD

Sat Jul 20, 2019 6:56 pm

You do not have 5 independent power supplies. All the voltage rails are linked and the design dictates the amount of power available to each voltage rail. You can not divert power to one rail by leaving the others unused. The only way is to provide more power from the external power supply. 150 W at least for the max ratings of the power supply you quote, although 120W should be more than adequate for the set up you quote unless you start making additions.
If I understand you correctly, you mean that I can not expect to get the full 60W only from the 5V rail. But why does the datasheet of the casing state, that the 5V rail can supply 10A? Wouldn't that be at least 50W? According to my calculation I only need 27W (overall, for the entire setup) from the 5V rail (which should provide 50W if I am not mistaken) - assuming that the RPi and the HDDs are under full load, which is probably not the case. Do you mind explaining me how you got to approx. 145W? I think I am missing something.

andrum99
Posts: 707
Joined: Fri Jul 20, 2012 2:41 pm

Re: Raspberry Pi 4 & HDD

Sat Jul 20, 2019 7:07 pm

Your best bet is to connect the two hard disks using a powered USB hub. The Pi does not supply enough power from its USB ports to power two hard disks at the same time.

kuchenkruste
Posts: 9
Joined: Thu Jul 18, 2019 11:22 am

Re: Raspberry Pi 4 & HDD

Sat Jul 20, 2019 7:36 pm

Your best bet is to connect the two hard disks using a powered USB hub. The Pi does not supply enough power from its USB ports to power two hard disks at the same time.
But it doesn't need to, or am I mistaken? The power cables for the HDDs are not connected to the RPi or its USB-Ports but directly to the power supply. So the USB-Ports only need to provide a little amount of power for the data cable of the HDDs. By the way, I already tried a powered USB-Hub. The outcome was the same, so the problem must be somehow connected to the power supply of the RPi and the HDDs and not to the USB ports.

carbone
Posts: 19
Joined: Tue Jul 16, 2019 6:09 pm
Location: Sheffield UK

Re: Raspberry Pi 4 & HDD

Sat Jul 20, 2019 7:47 pm

kuchenkruste wrote:
Sat Jul 20, 2019 6:56 pm
You do not have 5 independent power supplies. All the voltage rails are linked and the design dictates the amount of power available to each voltage rail. You can not divert power to one rail by leaving the others unused. The only way is to provide more power from the external power supply. 150 W at least for the max ratings of the power supply you quote, although 120W should be more than adequate for the set up you quote unless you start making additions.
If I understand you correctly, you mean that I can not expect to get the full 60W only from the 5V rail. But why does the datasheet of the casing state, that the 5V rail can supply 10A? Wouldn't that be at least 50W? According to my calculation I only need 27W (overall, for the entire setup) from the 5V rail (which should provide 50W if I am not mistaken) - assuming that the RPi and the HDDs are under full load, which is probably not the case. Do you mind explaining me how you got to approx. 145W? I think I am missing something.
P=VI
3.3 x 10 = 33 etc.

Total is actually 148.8 W.

You can not get more power out than goes in so the available power will be in ratio to that available due to the design. I doubt PSUs for ITX exist that can dynamically distribute power. If the specs are as you quote it must require a larger external supply to achieve those values.

kuchenkruste
Posts: 9
Joined: Thu Jul 18, 2019 11:22 am

Re: Raspberry Pi 4 & HDD

Sat Jul 20, 2019 8:21 pm

Total is actually 148.8 W.

You can not get more power out than goes in so the available power will be in ratio to that available due to the design. I doubt PSUs for ITX exist that can dynamically distribute power. If the specs are as you quote it must require a larger external supply to achieve those values.
It took me long enough, but now I got it. :D You summed up all the different rails (3.3V * 10A + 5V * 10A + 5V * 2A + 12V * 4.5A + 12V * 0.15A = 148.8W).

How is it, that the manufacturer of the casing specifies, that external PSUs up to 120W are possible? Wouldn't that mean, that it is impossible to reach the maximal output on all rails?

kuchenkruste
Posts: 9
Joined: Thu Jul 18, 2019 11:22 am

Re: Raspberry Pi 4 & HDD

Sat Jul 20, 2019 8:28 pm

kuchenkruste wrote:
Sat Jul 20, 2019 8:21 pm
Total is actually 148.8 W.

You can not get more power out than goes in so the available power will be in ratio to that available due to the design. I doubt PSUs for ITX exist that can dynamically distribute power. If the specs are as you quote it must require a larger external supply to achieve those values.
It took me long enough, but now I got it. :D You summed up all the different rails (3.3V * 10A + 5V * 10A + 5V * 2A + 12V * 4.5A + 12V * 0.15A = 148.8W).

How is it, that the manufacturer of the casing specifies, that external PSUs up to 120W are possible? Wouldn't that mean, that it is impossible to reach the maximal output on all rails?
So to sum it all up: If I connect a separate power supply to the RPi the 60W PSU should be sufficient for the two HDDs?

carbone
Posts: 19
Joined: Tue Jul 16, 2019 6:09 pm
Location: Sheffield UK

Re: Raspberry Pi 4 & HDD

Sat Jul 20, 2019 8:41 pm

kuchenkruste wrote:
Sat Jul 20, 2019 8:21 pm
Total is actually 148.8 W.

You can not get more power out than goes in so the available power will be in ratio to that available due to the design. I doubt PSUs for ITX exist that can dynamically distribute power. If the specs are as you quote it must require a larger external supply to achieve those values.
It took me long enough, but now I got it. :D You summed up all the different rails (3.3V * 10A + 5V * 10A + 5V * 2A + 12V * 4.5A + 12V * 0.15A = 148.8W).

How is it, that the manufacturer of the casing specifies, that external PSUs up to 120W are possible? Wouldn't that mean, that it is impossible to reach the maximal output on all rails?
Perhaps that is the largest one they themselves supply or it is a limitation of the connector used or maybe you need forced cooling to run at max power.
Last edited by carbone on Sat Jul 20, 2019 9:22 pm, edited 1 time in total.

carbone
Posts: 19
Joined: Tue Jul 16, 2019 6:09 pm
Location: Sheffield UK

Re: Raspberry Pi 4 & HDD

Sat Jul 20, 2019 8:46 pm

kuchenkruste wrote:
Sat Jul 20, 2019 8:28 pm
kuchenkruste wrote:
Sat Jul 20, 2019 8:21 pm
Total is actually 148.8 W.

You can not get more power out than goes in so the available power will be in ratio to that available due to the design. I doubt PSUs for ITX exist that can dynamically distribute power. If the specs are as you quote it must require a larger external supply to achieve those values.
It took me long enough, but now I got it. :D You summed up all the different rails (3.3V * 10A + 5V * 10A + 5V * 2A + 12V * 4.5A + 12V * 0.15A = 148.8W).

How is it, that the manufacturer of the casing specifies, that external PSUs up to 120W are possible? Wouldn't that mean, that it is impossible to reach the maximal output on all rails?
So to sum it all up: If I connect a separate power supply to the RPi the 60W PSU should be sufficient for the two HDDs?
Yes that is probably the easiest and cheapest option. Though you could probably use an 80W or 90W external supply

kuchenkruste
Posts: 9
Joined: Thu Jul 18, 2019 11:22 am

Re: Raspberry Pi 4 & HDD

Sat Jul 20, 2019 9:26 pm

Yes that is probably the easiest and cheapest option. Though you could probably use an 80W or 90W external supply
I will try the cheaper option first :D

I really hope my problem is solved with the new power supply. Nevertheless, thank you very much for your help!

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