One thing you could do is check for the MaxClients setting. Run the following commands as root:
1. # grep MaxClients /usr/local/apache/conf/httpd.conf
MaxClients output here
2. ps axf|grep httpd|wc -l
Actual clients output here
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If that does not seem to work, your load is down and everything else seems to be running fine, you may want to check the size of your logs as they can dramatically decrease your server's performance. To do this, run the following from root:
# cd /usr/local/apache/logs/ or /usr/local/apache/domlogs <-- change your directory to the apache logs directory.
# ll -h <-- Will show the size of your files in that directory.
# rm -dfr /path/to/logs (ex: rm -dfr /usr/local/apache/domlogs/logfilename) <-- Deletes the domlogs file.