On 28.10.2024 15:41, B.M. wrote:
Hi,
I have a small server (Raspberry Pi 4 in fact) and since a couple of weeks it
repeatedly hangs after some days until I reboot it (after months of uptime
without any problem - but I changed a few things in the meantime, so maybe
load is now higher than before).
At least after installing watchdog it reboots now automatically.
Here some top output just before reboot:
load avg 20 18 12 (so: much higher than normal, e.g. 1.1 1.2 1.5 or so)
MiB Mem: 3835 total, 618 free, 1194 used, 2264 buff/cache
MiB Swap: 1024 total, 600 free, 430 used, 2640 avail
Processes with highest CPU usage:
kswapd0 with 80%
java (openhab) 41%
kworker/08:10+events_unbound 21%
pg_dump 18%
Processes with highest Mem usage:
java (i.e. openhab) with 626678 virt, 22%
postgres 338824 virt
postgre 338800 virt
From my understanding, there is enough memory available, even swap usage
wouldn't be necessary, since buff/cache is about 50% of physical memory. Is
this correct? But than: why is it going to hang afterwards, or why this
extreme load?
The only swap device available is zram, no swap partition, no swap file. The
system runs on btrfs.
Any ideas?
Does it hangs completely, i.e. no ssh, no video, no ping?
It is hard to suggest anything concrete without logs. You can list logs
from previous boot with journalctl:
# journalctl -b -1
# journalctl -b -2
# journalctl -b -3
etc.
zram probably is a bad idea, in your case, because your limited hardware
wastes CPU cycles on compression and
active processes will eventually run out of free memory resulting in
heavy swapping and storage IO.
And in your case there is no swap partition "safety net", which is, as
they say, better to have it and don't need it, than need it and don't
have it.
btrfs in my experience is also too resource hungry and requires manually
disabling CoW on write intensive files for better storage IO performance.
Monitoring temperatures is a good way to rule out another possible culprit.
--
With kindest regards, Alexander.
Debian - The universal operating system
https://www.debian.org
