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How do I enable Piped Logs for Apache Web Server

Article ID: 2066, created on Aug 2, 2007, last review on Apr 8, 2015

  • Plesk for Linux/Unix


Various issues related to Apache and the Horde web interface. For example:

  • "Login failed" message or a blank page in Horde web interface

  • Unable to send emails from Horde Webmail

  • Web sites not opening properly.

  • Apache does not want to start up.


If you try to host more than 300 websites on the server, Apache may fail to work because of a problem involving the file descriptors limit. By default, Apache can only handle 1024 file descriptors.

Every Virtual Host requires 2 or 4 (if HTTPS is enabled) log files, so with this scheme only around 300 domains can be hosted without an Apache recompilation. See article #260 for more details on recompiling.


Run the following command to see the root of the Apache processes tree:

# ps axf | grep httpd | grep -v grep
2718 ? Ss 0:00 /usr/sbin/httpd
2720 ? S 0:00 \_ /usr/sbin/httpd
2721 ? S 0:03 \_ /usr/sbin/httpd
3821 ? S 0:00 \_ /usr/sbin/httpd
3901 ? S 0:00 \_ /usr/sbin/httpd

Then check the number of open file descriptors using the root PID (2718):

# ls /proc/2718/fd/ | wc -l

If the returned value is more than 1024, this means that Apache does not have enough file descriptors and may fail to work correctly.


The Piped Logs feature that was implemented in Parallels Plesk 8.2 allows you to host up to 900 domains safely on the default Apache web server. If you have more than 900 domains, you will still have to recompile Apache and certain other system packages as described in article #260.

To enable Piped Logs on Plesk 11.5 or newer, go to Tools & Settings > Apache Web Server and check "Piped logs" checkbox.

To enable Piped Logs on earlier versions:

  1. Log in to the server shell.
  2. Issue this command:

    # mysql -uadmin -p`cat /etc/psa/.psa.shadow` psa -e "replace into misc (param,val) values ('apache_pipelog', 'true');"
  3. Rebuild the Apache configuration:

    # $PRODUCT_ROOT_D/admin/sbin/websrvmng -v -a

Search words:

Login failed

Unable to send emails from Horde Webmail

FastCGI-stderr: PleskUtilException:

502 bad gateway error on all domains on the server

Unable to open logs

login is not possible

Can not reconfigure web server configurations: Unable to execute httpdmng:

nginx: [emerg] open()

Apache does not want to start up

failed login Horde


nginx: [emerg] open(

Starting httpd: httpd: Syntax error on line 221 of /etc/httpd/conf/httpd.conf: Syntax error on line 7 of /etc/httpd/conf.d/zz010_psa_httpd.conf: Syntax error on line 152 of /usr/local/psa/admin/conf/vhosts_bootstrap.conf: Could not open configuration file /var/www/vhosts/ No such file or directory

horde is broken

56797cefb1efc9130f7c48a7d1db0f0c a914db3fdc7a53ddcfd1b2db8f5a1b9c 29d1e90fd304f01e6420fbe60f66f838

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