Random 503

lefteris

Hello everyone.
using v11 and OLS i experience a random 503 errors on websites.
those errors are instant. After 1 second website is back.

which logfiles should i investigate to find the reason of those 503 errors?

twest

There's a lot of old threads about this, suggest checking some of those out, for example:
https://community.enhance.com/d/558-nproc-limit-on-every-account/54

lefteris

yes i am aware of this thread, but i am not using any cgroups limits

adil

lefteris i am not using any cgroups limits

Maybe that's your issue ?

lefteris

yes it could be, on which logfiles such errors are logged?

adil

From an old ticket, Adam response was :

The litespeed error log will show you it happening in /var/local/enhance/openlitespeedlogs/error.log but it won't show you why it happened. A 503 means OLS couldn't connect to your PHP worker.

But, he suggest to run when the 503 happens :
top -b -n 1

which will help to investigate what's/who eating the resources.

Other members of the forum may have more experience to direct you, but I suggest to add some limits to the websites, cPFence has a good article about this (first two steps, no need for cPFence itself) :
https://my.cpfence.app/knowledgebase/56/How-to-Address-High-Server-Load-Issues-with-cPFence.html

lefteris

Thank you Adil

gmakhs

lefteris my guess is that is either out of ram, or nproc limit reached, you should add limits to your websites this way you will manage to pin down the one creating the problem and focus on it .

lefteris

has anyone else see this kind of log?
this is what i saw when website generated a 503 error.
these are google crawler ip addresses

[NOTICE] [173547] [66.249.66.39:36158-1#domain.tld] ERROR in Linux Aio read: Illegal seek (29)
[NOTICE] [173547] [66.249.66.39:36158-1#domain.tld] LsAioReq file read error io_complete error: Illegal seek

gmakhs

lefteris I dont think a notice like that can cause 503 error, 503 is a php related error most of the times, for some reason php fails,

xyzulu

@lefteris why not upgrade to v12?

gmakhs

xyzulu LEt me share a stereotype with you

1) He is greek
2) Most Greek websites run on GPL(cracked) Plugins and themes 80% approximately
3) He has no limits per website on resources
4) Once of the website probably creating too many nproc and causing the issue

5) I might be wrong and he is the exception, so then one or more websites consume allavailable resources, updating to V12 is good idea ofcourse but won't solve his problem