Issue Server started to be very very slow

[Maxim]

Hello!

I use Plesk already few years and first time have issue like this.

6 of September my server started experienced high load you can clearly see it on this graph.
Screenshot

And this is information about last week
Screenshot

This is information about CPU usage.
Screenshot

Before it was maximum 20%.

it wasn't any changes done that day from our side or our admin's side.

Now all sites work not stable ( sometimes sites, which had stable server response 100ms before, started sometimes work 6-10 seconds and sometimes 100ms ).

And CPU & Apache CPU & MySQL CPU very high.
Screenshot


We asked different server admins about help and even after their optimization everything not came back to normal state. Server still work not stable.

We have only a few thousands ( 2-4k ) of visitors per day for all our sites and powerful server.

Our VPS work much better with fewer resources available.

Do you have any idea why this happened and how we can fix that?

Can it be some problems with PLESK?

 

[pleskpanel]

Can it be some problems with PLESK?

You might need to do some research but at this point in the process, it's difficult to ascertain that Plesk is the cause based purely on your CPU graphs.

If you have mod status installed but not configured (in this case we'll assume CentOS), go to /etc/httpd/conf.modules.d and add this file if not already present:

status.conf

with the following contents:

<IfModule mod_status.c>

# ExtendedStatus controls whether Apache will generate "full" status
# information (ExtendedStatus On) or just basic information (ExtendedStatus
# Off) when the "server-status" handler is called. The default is Off.

ExtendedStatus On

<Location /server-status>
SetHandler server-status
Order deny,allow
Deny from all
Allow from 127.0.0.1 localhost ADD_YOUR_PUBLIC_IP_HERE
</Location>

</IfModule>

Now restart apache:

# service httpd restart

Then browse to the http://server IP/server-status and take a look at the information to determine a bit more about the requests hitting your VPS. Look at the requests being processed per second; some of this could be quite revealing and could identify opportunities to change your configuration beyond whatever optimization steps have been taken.

PS: "Powerful server" is very relative based on underlying hardware, the quality, and the current state. If you're running a VPS, you're subject to a whole litany of additional factors such as contention (let's say another tenant on the same hardware starts to experience extremely high traffic loads causing slow I/O which may affect other VPS instances on the same hardware).

PPS: Good luck!

 

[Bitpalast]

You could run
# watch "ps aux | sort -nrk 3,3 | head -n 20"
on the console to see the top cpu load processes as they happen.

You could run
# ps aux | grep httpd
or
# ps aux | grep apache
to find the top Apache (httpd) processes, then read the process id and run
# strace -p <process id>
to see details on what the high load process is doing.

 

[Maxim]

You could run
# watch "ps aux | sort -nrk 3,3 | head -n 20"
on the console to see the top cpu load processes as they happen.

You could run
# ps aux | grep httpd
or
# ps aux | grep apache
to find the top Apache (httpd) processes, then read the process id and run
# strace -p <process id>
to see details on what the high load process is doing.

This is result of
# watch "ps aux | sort -nrk 3,3 | head -n 20"
Screenshot


This is result of
# ps aux | grep httpd
# ps aux | grep apache
Screenshot

As i see here is not so much information.

 

[Bitpalast]

It is clearly an issue with the offentligaaffarer.se domain. There may be bad bots hitting it. You can check the access log of the domain. Either an attack is going on or scripta in the domain are poorly written.

When you disable the domain for testing the sever speed for others will greatly increase You will need to find out what is causing the high load in that domain.