Out Of Memory Error (Fix Common Problems)

[Jaytie]

Good evening,

so I'm following the advice and opening a thread after seeing an "Out of memory" Error in my Fix Common Problems Plugin.

 

After looking at the logs, it might have something to do with Rsync.

Found this in the logfile:

Feb  9 16:05:25 Dockerbox kernel: oom-kill:constraint=CONSTRAINT_NONE,nodemask=(null),cpuset=de0cfc44e0f23b22886296a3fdf0b85379af75a1e42099b33f9043bbcc605304,mems_allowed=0,global_oom,task_memcg=/,task=avahi-daemon,pid=21551,uid=61
Feb  9 16:05:25 Dockerbox kernel: Out of memory: Killed process 21551 (avahi-daemon) total-vm:3607048kB, anon-rss:3601876kB, file-rss:4kB, shmem-rss:2804kB, UID:61 pgtables:7092kB oom_score_adj:0

 

I started/configured a rsync daemon folling this post:

I want my Unraid Server  to be a rsync target for Synology Hyper Backup, which worked and is actually running right now.

 

Logfiles attached. Can you give me some further information?

 

diagnostics-20230210-0057.zip

[Jaytie]

Hello again,

no ideas yet?

 

Just had another "out of memory" error in my logs, which killed one docker-container.

I'm not 100% sure, but it might have happened as I accessed a folder with a lot of pictures on my Nextcloud with the NC Web-Interface.

 

Added the diagnostic files again.

 

Help would me much appreciated!

 

Greetings

diagnostics-20230213-1650.zip

[JorgeB]

If it keeps happening try limiting more the RAM for VMs and/or docker containers, alternatively a small swap file on disk might help, you can use the swapfile plugin:

 

https://forums.unraid.net/topic/109342-plugin-swapfile-for-691/

[Jaytie]

I was now able to reproduce it. When accessing a nextcloud folder with a lot of thumbnails to create, memory usage of the nextcloud container bumps up and the 'out of memory' error occurs.

 

39 minutes ago, JorgeB said:

If it keeps happening try limiting more the RAM for VMs and/or docker containers

 

Okay thanks! Whats the best way to do this? Should I set a parameter here:

 

 

Like:

"--memory=2G"

 

 

Will have a look at the swapfile, thanks!

 

 

Edit:

I'm a little bit confused here. As I wrote in my initial post, it also runs out of memory, when a client reaches the Unraid-Server via rsync.

Does somebody have a clue, why that's the case?

 

Edited February 13, 2023 by Jaytie

[Jaytie]

The Swapfile-Plugin helps with the symtoms but the problem is still present.

Its the "avahi-daemon" that uses all the memory.

 

 

[Jaytie]

Another update and hopefully the solution for my issue:

 

As mentioned above, the issue reproducedable occured, when connecting with the Hyper Backup Client via rsync to Unraid.

I guess because of failing reverse lookups the avahi-daemon used all the ram and most of the CPU:

 

Feb 10 00:55:03 Dockerbox  rsync[2997]: connect from 192.168.10.2 (192.168.10.2)
Feb 10 00:55:03 Dockerbox  rsyncd[2997]: name lookup failed for 192.168.10.2: Name or service not known
Feb 10 00:55:03 Dockerbox  rsyncd[2997]: connect from UNKNOWN (192.168.10.2)

 

Also Hyper Backup wasn't able to connect during that time. Eventually the system was out of memory killed a process (not always the same) and Hyper Backup connected.

 

Solution:

 

I added the line

 

reverse lookup = no

 

to my

/boot/custom/etc/rsyncd.conf

 

This results in no more failed name lookups, Hyper Backup connects instantly and Ram usage stays as it should.

 

I hope this was the main issue. Maybe this will help someone in the future.