Help. Advice needed.

I had been reading about the advantages of booting the Rpi 4 from a USB 3 drive. I bought a 250Gb drive, less than £20. I followed the instructions on Youtube, doing a full update of Raspbian, doing rpi-update, copying the the SSD-card to the drive, and using raspi-config to make the system boot from the USB 3 drive if no SSD card were present. But when I tried to boot from the USB 3 drive it complained that recover4.elf not compatible . I logged onto the raspberrypi.org forum and some patient people tried to help. I discovered that the file recover4.elf in the mmcblk0p1 partition was indeed from June 2019. I got hold of the latest from the Raspberry Pi git and copied it in. Alas, that bricked my SSD card, and booting got no further than the big coloured square thingy. Fortunately, I had a recent backup of Raspbian on another card, which booted up. But now, whenever I go to the raspberrypi.org forum, for further advice, after a few seconds, the mouse and keyboard lock up, leaving a switch-off as the only option. It never rains … . I have not yet discovered whether the mouse and keyboard would have locked up anyhow, though tentative efforts to write a textfile were successful. Anyway, how can a website interfere with those peripherals? Or is it a WiFi thing? Help!

I have found the Raspberry Pi forum stuff.

It all sounds a bit convoluted!!! Setting up a boot from USB3 from an existing SD card just worked here.

I do notice that the fdisk -l results on the other forum do show rather more partitions that I would expect. I only see two here.

The RPi400 using the USB3 drive no longer has the source SD card in it, fdisk shows this :-

Disk /dev/sda: 465.8 GiB, 500107862016 bytes, 976773168 sectors
Disk model: Portable SSD T3 
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 33553920 bytes
Disklabel type: dos
Disk identifier: 0xebabf75b

Device     Boot  Start       End   Sectors   Size Id Type
/dev/sda1         8192    532479    524288   256M  c W95 FAT32 (LBA)
/dev/sda2       532480 976773167 976240688 465.5G 83 Linux

An RPi4 that only has an SD card shows this :-

Disk /dev/mmcblk0: 29.7 GiB, 31914983424 bytes, 62333952 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x3f0e571c

Device         Boot  Start      End  Sectors  Size Id Type
/dev/mmcblk0p1        8192   532479   524288  256M  c W95 FAT32 (LBA)
/dev/mmcblk0p2      532480 62333951 61801472 29.5G 83 Linux

For convenience I have copied Gavin’s to here for easy comparison :-

Disk /dev/mmcblk0: 14.7 GiB, 15720251392 bytes, 30703616 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x3cca53c6

Device Boot Start End Sectors Size Id Type
/dev/mmcblk0p1 8192 3193359 3185168 1.5G e W95 FAT16 (LBA)
/dev/mmcblk0p2 3193360 30703615 27510256 13.1G 5 Extended
/dev/mmcblk0p5 3194880 3260413 65534 32M 83 Linux
/dev/mmcblk0p6 3260416 3784701 524286 256M c W95 FAT32 (LBA)
/dev/mmcblk0p7 3784704 30703615 26918912 12.9G 83 Linux


Disk /dev/sda: 232.9 GiB, 250059350016 bytes, 488397168 sectors
Disk model: Data USB 3.0 
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: dos
Disk identifier: 0x3cca53c6

Device Boot Start End Sectors Size Id Type
/dev/sda1 8192 3193359 3185168 1.5G c W95 FAT32 (LBA)
/dev/sda2 3193360 488397167 485203808 231.4G 5 Extended
/dev/sda5 3194880 3260413 65534 32M 83 Linux
/dev/sda6 3260416 3784701 524286 256M c W95 FAT32 (LBA)
/dev/sda7 3784704 488397167 484612464 231.1G 83 Linux

Whar does the team think?

See the WROCC Jan 2021 issue for even more fun on these lines. It predated USB booting on the Pi 400 (Sept 2020) and showed how to have a multi-partition SD card that would boot into Linux or RISC OS depending on a switch on the GPIO pins that was ‘RISC OS’ or ‘Linux’. The key was to use the strange command ‘dev_tree=’ in CONFIG.TXT.

The gory detail (for those who do not subscribe to WROCC) is here.

It turned out, I am 99% sure, that the kbd/mouse locking up was because my back-up version of Raspbian was overclocked to 2.1Ghz and was set to run in 64-bit mode. I just managed to do sudo nano /boot/config.txt and edit it to run in 32-bit mode at 1.75Ghz and I was back in business with a functioning machine. I then did a full update and tried to save the back-up card to the old card (back-up^2 card?), which was in a USB card-reader. That took a long while, and the screen-blanker kicked in. I usually tap the space bar to bring the screen back up, but by mischance the cursor was sitting on top of the Cancel button in the card-copyier’s window. The unintended interruption apparently did for the old card, which I suspect got corrupted. I have disabled screen-blanking now. I then recopied my newly functioning, newly updated SD-card to the USB 3 device. But no cigar. It still says incompatible recover4.elf . It looks as if full update does not update the firmware. So I am back to square one, and only slightly wiser.

Postscript

Panic over. I downloaded the Raspberry Pi Imager application and used it to install a full Raspbian distribution on the USB 3 device. It all worked without a hiccough. The micro-SD card can now be kept in a drawer as a backup.