Re: Boot from USB on RPi4 8GB?
- In reply to: William Carson via freebsd-arm : "Re: Boot from USB on RPi4 8GB?"
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Date: Mon, 31 May 2021 03:49:32 UTC
On 2021-May-30, at 16:54, William Carson via freebsd-arm <freebsd-arm at freebsd.org> wrote: >> On May 30, 2021, at 4:08 PM, Mark Millard <marklmi@yahoo.com> wrote: >> >> On 2021-May-30, at 13:50, Mark Millard via freebsd-arm <freebsd-arm at freebsd.org> wrote: >> >>> On 2021-May-30, at 10:59, William Carson via freebsd-arm <freebsd-arm at freebsd.org> wrote: >>> >>>>> . . . >>>>> I use a USB3 SSD that has small enough power requirements >>>>> to not require a powered hub. (I also use a 5.1V 3.5A >>>>> power supply as part of that context.) I've never tried >>>>> spinning rust or higher powered USB3 media. >>> >>> I view the power supply that I use as just giving a little >>> more margin, not as a way to increase what the devices >>> total to. >>> >>>> . . . I'm not sure what's considered "high powered" but the Samsung tech specs say this particular model uses 5.7 W on average and 10.0 W maximum. But it does seem curious that the Raspberry PI OS will boot this disk without issue, so I don't think it's the drive. I also tried a Samsung 950 PRO using a different enclosure (QNINE NVME Enclosure, M.2 PCIe SSD (M Key) to USB 3.0 External Case), but it behaved the same. >>> . . . >>> >>> Then you need to use a powered hub for that device. >> >> I should have just referred to independent power. You >> had written: >> >> QUOTE >> I'm trying to use a SAMSUNG (MZ-V7E500BW) 970 EVO SSD 500GB - M.2 NVMe, attached via the Geekworm X872 M.2 NVMe 2280/2260/2242/2230 SSD Expansion Board. >> END QUOTE >> >> https://geekworm.com/products/raspberry-pi-4-x872-m-2-nvme-2280-2260-2242-2230-ssd-expansion-board >> >> shows that it has its own power connector and has an image >> that says "please power x872 via DC Jack of XH2.54 connector >> if SSD is not recognized or low power". Later text on the >> page says: >> >> QUOTE >> Specifications: >> Power Supply >> • 5Vdc +/-5% , Powered by Raspberry Pi USB port >> • 5Vdc via DC power jack or XH2.5 connector, Extra power for the SSD >> END QUOTE >> >> So, if I gather right, you need to connect a power >> supply to the X872 and another to the RPi4B. >> >> Another image says "Note: NOT recommended to use SAMSUNG SSD, >> if use SAMSUNG SSD, please close WiFi". Later text on the page >> says the same. > > A-ha, indeed. I just noticed that as well. I've gone ahead and ordered a supplementary power supply and a lower-power NVMe to do more testing. I'll send an update once I've received and tested them. > > Thank you for hopefully pointing me in the right direction. I do not know if the "supplementary power supply" would be sufficient for the existing drive to work, but it is likely necessary. Similarly for any other drive that could require a significant portion of the 1.2A at times. (I've no clue what else you have plugged into USB or how much power(/current) those devices take (if any). So I do not know what to subtract from the 1.2A.) The USB3 SSDs that I'm using are based on: ATA Version is: ATA8-ACS, ACS-2 T13/2015-D revision 3 SATA Version is: SATA 3.0, 6.0 Gb/s (current: 6.0 Gb/s) This helps explain why I've got no power problem: older technology. Note that SATA 3.0 can be somewhat faster than the original USB3 already, at least in some respects. >> https://www.raspberrypi.org/documentation/hardware/raspberrypi/power/README.md >>> lists: >>> >>> "Maximum total USB peripheral current draw" as: 1.2A , >>> which at 5.1V is 6W. (Possibly should have listed the 6.12W figure.) >>> That figure is the total for all USB devices attached >>> that are not powered independently. >>> >>> That document also says that a 5.1V supply is required, >>> not 5V. >>> >>> The power supply that the RPi folks supply is 5.1V @ 3A >>> or 15.3W. Even the 5.1V 3.5A power supply that I use >>> only multiplies out to 17.85W. >> > > === Mark Millard marklmi at yahoo.com ( dsl-only.net went away in early 2018-Mar)