Weird reboot behaviour on RPi 4 B

I boot the system from a external USB HDD, which works fine. This HDD is powered by the Pi itself.

I have another USB HDD connected, just for daily system backups. This one has it’s own power supply.

When both HDDs are connected and I try to reboot, it just fails. It works when only the system HDD is connected, I have to plug in the backup drive after booting.

My first thought was, that this could be a power issue, bc the PI boosts its CPU freq to max for 20 seconds on boot up to speed up the boot process. I disabled this feature, but the behaviour didn’t change.
I tried other USB ports, with no success.

Any ideas? :slight_smile:

Ok might not be related to your issue but you should try to avoid operating a HDD without dedicated PSU, because RPI4 USB ports are not designed to fully power HDD. At the moment this might gonna work in your case but your are running a risk to get data corrupted due to power shortage and voltage drops. Especially during boot this could be the case. We had quite some issues where user lost their entire system this way.

You can watch potential issues be checking for kernel error message

dmesg -l err,crit,alert,emerg

looking to your issue, could you share following

cat /boot/cmdline.txt
cat /etc/fstab
lsblk -o name,fstype,label,size,ro,type,mountpoint,partuuid,uuid
dietpi@DietPi:~$ dmesg -l err,crit,alert,emerg
[    2.115512] bcm2708_fb soc:fb: Unable to determine number of FBs. Disabling driver.

This is something about framebuffer (?), but I don’t care, because I just use SSH?

dietpi@DietPi:~$ cat /boot/cmdline.txt
root=PARTUUID=8b0ac6f5-02 rootfstype=ext4 rootwait net.ifnames=0 logo.nologo quiet console=tty1
dietpi@DietPi:~$ cat /etc/fstab
# You can use "dietpi-drive_manager" to setup mounts.
# NB: It overwrites and re-creates physical drive mount entries on use.

tmpfs /tmp tmpfs size=1922M,noatime,lazytime,nodev,nosuid,mode=1777
tmpfs /var/log tmpfs size=50M,noatime,lazytime,nodev,nosuid,mode=1777

# MISC: ecryptfs, vboxsf (VirtualBox shared folder), gluster, bind mounts


PARTUUID=8b0ac6f5-02 / ext4 noatime,lazytime,rw 0 1
PARTUUID=8b0ac6f5-01 /boot vfat noatime,lazytime,rw 0 2
UUID=57d98fa6-b50d-40c6-b155-0a4f644b312a /mnt/bup ext4 noatime,lazytime,rw,nofail,noauto,x-systemd.automount

dietpi@DietPi:~$ lsblk -o name,fstype,label,size,ro,type,mountpoint,partuuid,uuid
sda                 117.4G  0 disk
├─sda1 vfat           128M  0 part /boot      8b0ac6f5-01                          22B4-00D8
└─sda2 ext4         117.3G  0 part /          8b0ac6f5-02                          f406011c-615d-4dee-abe8-501b09f46b7b
sdb                 465.8G  0 disk
└─sdb1 ext4         465.8G  0 part /mnt/bup   77696e50-01                          57d98fa6-b50d-40c6-b155-0a4f644b312a

I will get a external HDD case with it’s own power supply and report if something changed.

would it be an option to swap HDD. Just for testing. To see how it behave to boot from the powered one while the other is connected as well. Or to use a pen stick to boot from instead of HDD?

Yes it works the other way around, the backup HDD without extra power and the boot drive with extra power (which is btw an SSD, I thought they need less power, but maybe still too much for Pi’s USB ports)

probably it takes longer for the non-powered HDD to spin up? But yeah RPI USB ports are not designed for this.