Raspi with USB HDD fails to boot

[freeman]

I have USB HUB with power supply 2A. My USB disk drive is Samsung 2.5", at 850mA. Raspi has 800mA power Suplay.
When connected Disk to HUB and to Raspi, i see strange messages from kernel on screen. Disk drive is working (i hear "ssss"). Raspi is freezing and not working. When i have plug off power from Raspi, it works continuesly, powered from USB UHB. Then after few tryies, blank screen, no reainbow screen at boot. I had to disconnect and put offline for 20 minutes, after that Raspi work ok, without hub and disk. What to do?
Screenshot is on my Raspi web server (http://freeman.myftp.org/?p=84)

[FTrevorGowen]

I have USB HUB with power supply 2A. My USB disk drive is Samsung 2.5", at 850mA. Raspi has 800mA power Suplay.
When connected Disk to HUB and to Raspi, i see strange messages from kernel on screen. Disk drive is working (i hear "ssss"). Raspi is freezing and not working. When i have plug off power from Raspi, it works continuesly, powered from USB UHB. Then after few tryies, blank screen, no reainbow screen at boot. I had to disconnect and put offline for 20 minutes, after that Raspi work ok, without hub and disk. What to do?
Screenshot is on my Raspi web server (http://freeman.myftp.org/?p=84)

I think your USB hub is "the problem", given your comments and that it looks very similar to these: http://www.cpmspectrepi.webspace.virgin ... rtHub.html
As you've discovered hubs of that type allow any PSU connected to "back power" via their USB bus lead. In your case this means that the Pi's PSU and the Hubs PSU are "fighting each other" to power the hub and any attached devices eg. your USB disk drive, leading to "instability" etc.. You need a better quality hub, that does not "back power" and is capable of powering the Pi and HDD via its ports. Note that standard hubs can only provide 500mA per port so it also needs either to have a higher current "charging port" or you'll need to use a Y cable for your drive. Better still, if your drive has its own power socket, get a suitable PSU to power it independently.
Trev.

[freeman]

Thank Trev for explain. I will try to buy 2A power source adapter to my Pi and not to use this bad HUB.
Do you know what is max power can be attached to Pi with very good Power Supply without any HUB? Is there any limit?

[freeman]

I have connected power supply 5V, 2A to Pi, and try again boot up with 2,5" HDD, but again failed. HDD did not spin up. What kind of power supply is perfect for Pi?

[FTrevorGowen]

I have connected power supply 5V, 2A to Pi, and try again boot up with 2,5" HDD, but again failed. HDD did not spin up. What kind of power supply is perfect for Pi?

The Pi itself only needs a good 5V 1A PSU (or a very good 5V 850mA one like the Sony Ericsson one discussed here: http://www.cpmspectrepi.webspace.virgin ... plies.html ) but the Pi cannot provide more than about 300mA to other devices via its USB ports because the main polyfuse which starts to activate around 750mA total current. Hence the Pi cannot supply the extra current (850mA IIRC) required by your HDD. That has to be either powered directly from another PSU or via an good external powered hub with a suitable PSU, preferrably one that doesn't "backpower" since you're using two PSU's. Such hubs + PSU cost around the same price of a Pi (in the UK). It is also possible to power both the Pi and such a hub from a single supply but that would need to be rated at something like 5V at 2.5 to 3.0A (upto 1A for the Pi and something plugged into the other USB port, and 2A for the 4 x 500mA ports on the external hub). Hope this makes things clearer.
Trev.

[freeman]

Thank You!
It clear the problem.
I need new usb hub witch good PSU.

[freeman]

Trev, i have read the page what you point to me. And the PSU from Sony Ericsson is the best, Voltage did not drop down below 5V over 0.7A of power consumption.