Websites sporadically unavailable

Websites sporadically unavailable

There can be various reasons why a website is not reachable. The first step is to check whether there are many MySQL processes:

mysqladmin processlist

If the affected website can already be identified here, you can analyze it in more detail.

As a standard option, the following commands are always available:

service mysql restart
service apache2 restart

This temporarily resolves most issues. Afterwards, it becomes more difficult to determine the actual cause.

With the following command, you can search the log files for websites with many accesses at the requested time (example from 00:00 to 09:59):

zgrep "1/Sep/2025:0" /var/www/vhosts/system/*/logs/access_log* | cut -d/ -f6 | sort | uniq -c | sort -nr | head -20

Once the affected domain has been identified, you can explicitly search for the specific file or vulnerability:

zgrep "1/Sep/2025:0[23]:" /var/www/vhosts/system/<domain>/logs/access_log* | awk '{print $7}' | sort | uniq -c | sort -nr | head -30

This will display the files with the most accesses. A common target is xmlrpc.php in WordPress, which should be disabled globally.