retrack

It worked, I have my eMMC system back!
 
Here are all the steps in case someone else has the problem and wants to repair his eMMC image...
 
1. download a previous Helios64 image from here...
https://wiki.kobol.io/download/
2. install the image on a microSD e.g. for Windows and macOS there is Etcher...
https://www.balena.io/etcher/
3a. boot your Helios64 with the microSD and Jumper 10, see here...
https://wiki.kobol.io/helios64/troubleshoot/#how-to-force-boot-from-microsd
3b. Alternative: from the serial console press a key on the keyboard while u-boot start. You will get the u-boot prompt.
From this prompt write and press enter. Helios64 will boot from SD... (thx @prahal)
run bootcmd_mmc1  
4. if you are logged in as root user (normal users must put a sudo in front of the commands) execute the following commands...
root@helios64:~# mkdir -p /mnt/system root@helios64:~# mount /dev/mmcblk2p1 /mnt/system root@helios64:~# cd /mnt/system/
5. The contents of the /mnt/system directory should now be filled with the contents of your eMMC....
root@helios64:/mnt/system# ll total 80 lrwxrwxrwx 1 root root 7 Aug 30 2020 bin -> usr/bin drwxr-xr-x 3 root root 4096 Sep 1 03:01 boot drwxr-xr-x 2 root root 4096 Oct 15 2020 dev drwxr-xr-x 110 root root 12288 Sep 1 03:01 etc drwxr-xr-x 2 root root 4096 Sep 22 2020 export drwxr-xr-x 5 root root 4096 Jun 10 04:12 home lrwxrwxrwx 1 root root 7 Aug 30 2020 lib -> usr/lib drwx------ 5 root root 4096 Oct 5 2020 lost+found drwxr-xr-x 4 root root 4096 Oct 15 2020 media drwxr-xr-x 2 root root 4096 Feb 9 2021 mnt drwxr-xr-x 4 root root 4096 Dec 2 2020 opt dr-xr-xr-x 2 root root 4096 Oct 15 2020 proc drwx------ 7 root root 4096 Aug 31 23:36 root drwxr-xr-x 2 root root 4096 Oct 15 2020 run lrwxrwxrwx 1 root root 8 Aug 30 2020 sbin -> usr/sbin drwxrwxr-x 2 root root 4096 Oct 5 2020 selinux drwxr-xr-x 6 root root 4096 Jun 10 03:18 srv dr-xr-xr-x 2 root root 4096 Oct 15 2020 sys lrwxrwxrwx 1 root root 42 Sep 1 03:01 thermal_zone0 -> /sys/devices/virtual/thermal/thermal_zone0 drwxrwxrwt 2 root root 4096 Oct 15 2020 tmp drwxr-xr-x 12 root root 4096 Nov 27 2020 usr drwxr-xr-x 14 root root 4096 Oct 6 2020 var  
6. now download the 3 old packages...
root@helios64:/mnt/system# wget http://armbian.hosthatch.com/apt/pool/main/l/linux-5.10.43-rockchip64/linux-dtb-current-rockchip64_21.05.4_arm64.deb root@helios64:/mnt/system# wget http://armbian.hosthatch.com/apt/pool/main/l/linux-5.10.43-rockchip64/linux-headers-current-rockchip64_21.05.4_arm64.deb root@helios64:/mnt/system# wget http://armbian.hosthatch.com/apt/pool/main/l/linux-5.10.43-rockchip64/linux-image-current-rockchip64_21.05.4_arm64.deb  
7. now changes the root directory...
root@helios64:/mnt/system# chroot /mnt/system root@helios64:/# pwd / root@helios64:/# ll total 50996 lrwxrwxrwx 1 root root 7 Aug 30 2020 bin -> usr/bin drwxr-xr-x 3 root root 4096 Sep 1 14:56 boot drwxr-xr-x 2 root root 4096 Sep 1 16:15 dev drwxr-xr-x 110 root root 12288 Sep 1 03:01 etc drwxr-xr-x 2 root root 4096 Sep 22 2020 export drwxr-xr-x 5 root root 4096 Jun 10 04:12 home lrwxrwxrwx 1 root root 7 Aug 30 2020 lib -> usr/lib -rw-r--r-- 1 root root 314304 Jul 8 19:32 linux-dtb-current-rockchip64_21.05.4_arm64.deb -rw-r--r-- 1 root root 11527696 Jul 8 19:32 linux-headers-current-rockchip64_21.05.4_arm64.deb -rw-r--r-- 1 root root 40290884 Jul 8 19:33 linux-image-current-rockchip64_21.05.4_arm64.deb drwx------ 5 root root 4096 Oct 5 2020 lost+found drwxr-xr-x 4 root root 4096 Oct 15 2020 media drwxr-xr-x 2 root root 4096 Feb 9 2021 mnt drwxr-xr-x 4 root root 4096 Dec 2 2020 opt dr-xr-xr-x 2 root root 4096 Oct 15 2020 proc drwx------ 7 root root 4096 Aug 31 23:36 root drwxr-xr-x 2 root root 4096 Oct 15 2020 run lrwxrwxrwx 1 root root 8 Aug 30 2020 sbin -> usr/sbin drwxrwxr-x 2 root root 4096 Oct 5 2020 selinux drwxr-xr-x 6 root root 4096 Jun 10 03:18 srv dr-xr-xr-x 2 root root 4096 Oct 15 2020 sys lrwxrwxrwx 1 root root 42 Sep 1 03:01 thermal_zone0 -> /sys/devices/virtual/thermal/thermal_zone0 drwxrwxrwt 2 root root 4096 Oct 15 2020 tmp drwxr-xr-x 12 root root 4096 Nov 27 2020 usr drwxr-xr-x 14 root root 4096 Oct 6 2020 var  
8. now installs the downloaded packages...
root@helios64:/# dpkg -i *.deb dpkg: warning: downgrading linux-dtb-current-rockchip64 from 21.08.1 to 21.05.4 (Reading database ... 62558 files and directories currently installed.) Preparing to unpack linux-dtb-current-rockchip64_21.05.4_arm64.deb ... Unpacking linux-dtb-current-rockchip64 (21.05.4) over (21.08.1) ... Selecting previously unselected package linux-headers-current-rockchip64. Preparing to unpack linux-headers-current-rockchip64_21.05.4_arm64.deb ... Unpacking linux-headers-current-rockchip64 (21.05.4) ... dpkg: warning: downgrading linux-image-current-rockchip64 from 21.08.1 to 21.05.4 Preparing to unpack linux-image-current-rockchip64_21.05.4_arm64.deb ... update-initramfs: Deleting /boot/initrd.img-5.10.60-rockchip64 Removing obsolete file uInitrd-5.10.60-rockchip64 stat: cannot stat '/proc/1/root/.': No such file or directory Unpacking linux-image-current-rockchip64 (21.05.4) over (21.08.1) ... Setting up linux-dtb-current-rockchip64 (21.05.4) ... Setting up linux-headers-current-rockchip64 (21.05.4) ... Compiling headers - please wait ... grep: /proc/cpuinfo: No such file or directory grep: /proc/cpuinfo: No such file or directory Setting up linux-image-current-rockchip64 (21.05.4) ... update-initramfs: Generating /boot/initrd.img-5.10.43-rockchip64 W: Couldn't identify type of root file system for fsck hook update-initramfs: Converting to u-boot format  
9. reset the root change with exit and restart your helios64 with reboot...
root@helios64:/# exit exit root@helios64:/mnt/system# reboot  
10. after a reboot you should now boot from the eMMC again...
root@192.168.180.5's password: _ _ _ _ __ _ _ | | | | ___| (_) ___ ___ / /_ | || | | |_| |/ _ \ | |/ _ \/ __| '_ \| || |_ | _ | __/ | | (_) \__ \ (_) |__ _| |_| |_|\___|_|_|\___/|___/\___/ |_| Welcome to Armbian 21.08.1 Buster with Linux 5.10.43-rockchip64 No end-user support: built from trunk System load: 74% Up time: 3 min Memory usage: 34% of 3.77G IP: 172.18.0.1 172.19.0.1 172.20.0.1 172.17.0.1 192.168.180.5 CPU temp: 66°C Usage of /: 87% of 15G [ 0 security updates available, 3 updates total: apt upgrade ] Last check: 2021-09-01 16:38 [ General system configuration (beta): armbian-config ] Last login: Wed Sep 1 16:26:23 2021 root@helios64:~# root@helios64:~# uname -a Linux helios64 5.10.43-rockchip64 #21.05.4 SMP PREEMPT Wed Jun 16 08:02:12 UTC 2021 aarch64 GNU/Linux root@helios64:~#  
11. if the eMMC was used you can see with mount...
root@helios64:~# mount | grep /dev/mmc /dev/mmcblk2p1 on / type ext4 (rw,noatime,nodiratime,errors=remount-ro,commit=600) /dev/mmcblk2p1 on /var/folder2ram/var/log type ext4 (rw,noatime,nodiratime,errors=remount-ro,commit=600) /dev/mmcblk2p1 on /var/folder2ram/var/tmp type ext4 (rw,noatime,nodiratime,errors=remount-ro,commit=600) /dev/mmcblk2p1 on /var/folder2ram/var/lib/openmediavault/rrd type ext4 (rw,noatime,nodiratime,errors=remount-ro,commit=600) /dev/mmcblk2p1 on /var/folder2ram/var/spool type ext4 (rw,noatime,nodiratime,errors=remount-ro,commit=600) /dev/mmcblk2p1 on /var/folder2ram/var/lib/rrdcached type ext4 (rw,noatime,nodiratime,errors=remount-ro,commit=600) /dev/mmcblk2p1 on /var/folder2ram/var/lib/monit type ext4 (rw,noatime,nodiratime,errors=remount-ro,commit=600) /dev/mmcblk2p1 on /var/folder2ram/var/cache/samba type ext4 (rw,noatime,nodiratime,errors=remount-ro,commit=600)  

Then yes the default fancontrol was super conservative. I have been running your suggestion a few days and I am now graphing temperature of SOC and disks to get better insights.

Looking into the fancontrol configuration, I think we were way too conservative on the settings making the fan going too early in higher RPM.
Plus we are not taking into consideration that the heatsink is already doing a pretty good job in passive mode.
 
I would recommend the following fancontrol settings until we provide a way to control the fan based on HDD temp instead :
 
# Helios64 PWM Fan Control Configuration # Temp source : /dev/thermal-cpu INTERVAL=10 FCTEMPS=/dev/fan-p6/pwm1=/dev/thermal-cpu/temp1_input /dev/fan-p7/pwm1=/dev/thermal-cpu/temp1_input MINTEMP=/dev/fan-p6/pwm1=40 /dev/fan-p7/pwm1=40 MAXTEMP=/dev/fan-p6/pwm1=110 /dev/fan-p7/pwm1=110 MINSTART=/dev/fan-p6/pwm1=60 /dev/fan-p7/pwm1=60 MINSTOP=/dev/fan-p6/pwm1=40 /dev/fan-p7/pwm1=40 MINPWM=40