I am using a RPi4 8GB in headless mode, running Raspbian (I know, I know, it is only 32 bits at present, so I only use 4 out of 8GB of RAM for now). The RPi4 is in an Argon ONE M.2 case, with a solid power supply (Raspberry official 3Amp RPi4 power supply), a 16GB SD card, and a 2TB SSD drive (WD Red Sa500 intern M.2 SATA SSD for NAS). There are no other peripherals. I SSH into the RPi. This follows the setup described in https://github.com/jerabaul29/strong_raspberry_pi_setup_hardening_robustifying/blob/main/README.md .

First things first: the SSD power consumption should be well within limits. 1.2A x 5.0V = 6000mW max supply on USB3, and the datasheet for the SSD names a max power consumption of 3800mW Max write operating. So I should not have power issues.

My issue is the following: after i) copying the SD card to the SSD using rpi-clone, ii) setting the boot order to SSD first, SD card second, iii) rebooting, I hit a situation where:

  • when both the SSD and the SD are present, the RPi boots sometimes from the SSD, sometimes (more often actually) from the SD card; this should not happen, as it should boot from the SSD first
  • when I remove the SD card, boot happens fine on the SSD each time, and all works well, which should confirm that i) my setup is correct, ii) all works actually well.

Any idea why the booting from SSD is problematic when the SD card is inserted? Any idea how to solve this? This is very strange to me, as I have another similar setup running in production but with a WD Green 240GB M.2 Internal SSD, otherwise everything identical, and the SD card is present, and I have never hit any problem then - it always boots from SSD and sees the SD card as an extra /dev/mmcblk0 device.

  • sees the SD card as an extra /dev/sda doesn't sound right ... isn't the SD card always /dev/mmcblk0 ?
    – Bravo
    Commented Jan 31, 2022 at 22:59
  • Yes, you are right, the partitions for the SD card are seen as /dev/mmcblk0p[1/2], and this is consistent with the github page. Fixing this now :) .
    – Zorglub29
    Commented Feb 1, 2022 at 8:26


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