SSD Unexpected_Power_Loss / POR_Recovery_Count on Reboot

[tjay]

Hi,

I’m using the Helios64 with Armbian 20.11 Buster ( 5.9.10-rockchip64)

 

On every reboot the SMART counter for  “Unexpected_Power_Loss (174)” /  “POR_Recovery_Count (235)”  incresses by one. I’ve seen this unexpected behaviour on Samsung, WD and Crusical SSDs …

 

Rebooting the box with

sync && echo 1 > /sys/block/sdX/device/delete && reboot

turns the disk friendly off, but shouldn’t this be done in systemd/kernel?  

[tjay]

Inspired by this topic https://forum.odroid.com/viewtopic.php?t=29069 I installed a shutdown script in /lib/systemd/system-shutdown:

#!/bin/bash

case "$1" in
    kexec)
       # Do not park disks when switching kernels.
       ;;
    *)
       for disk in /sys/block/sd* ; do
         echo 1 > /sys/class/block/${disk##*/}/device/delete
       done
       sleep 1
        ;;
esac

this works for my needs.

 

I don’t know if this problem is Helios64 specific, if not please move this topic to armbian common issues..

[gprovost]

Good point indeed, we need to experiment to see to which extend it is really needed.

 

Experimenting with the following inspired from the odroid thread you shared

 

#!/bin/bash

# Wait mdadm arrays are in clean state
[ -x /sbin/mdadm ] && /sbin/mdadm --wait-clean --scan

# Choose hdparm param
systemctl list-jobs | egrep -q 'reboot.target.*start' && YVAL='Y' || YVAL='y'

# Park all SATA disks.
if [ -x /usr/sbin/hdparm ]; then
   for DEV in /sys/block/sd* ; do
      [ -e $DEV ] && /usr/sbin/hdparm -$YVAL /dev/${DEV##*/}
   done
   sleep 3
fi

for DEV in /sys/block/sd* ; do
   echo 1 > /sys/class/block/${DEV##*/}/device/delete
done

 

[ShadowDance]

I've also noted the sudden power loss to drives and that it only happens during reboot, not regular shut down. When doing a regular shut down the drives seem to shut down one at a time, and when reboot:ing they lose power simultaneously.

 

Now, I'm wondering, what happens if the system is running from the drives and we're using a systemd script to stop them? Is there a chance that they will spin up again because another script is loaded or something similar? It may be a stupid question but I'm not very familiar with systemd. I imagine it should be the very last thing that's executed before the actual restart.

 

Edit: Side-question, is it actually necessary to power cycle the drives during reboot? Or could they be left running? Might that require changes to u-boot perhaps?

[aprayoga]

 

On 11/30/2020 at 8:01 PM, ShadowDance said:

Edit: Side-question, is it actually necessary to power cycle the drives during reboot? Or could they be left running? Might that require changes to u-boot perhaps?

Maybe it is not necessary and rely on SATA soft reset. U-Boot definitely needs to be modified to differentiate reboot and power on.