Files in Parallels Plesk

Plesk Panel

Plesk root directory /usr/local/psa
Version /usr/local/psa/version
Admin password is stored /etc/psa/.psa.shadow
Plesk configuration file /etc/psa/psa.conf
Restart Plesk /etc/rc.d/init.d/plesk restart

Apache

Main httpd configuration file /etc/httpd/conf/httpd.conf
Plesk httpd /etc/httpd/conf.d/zz010_psa_httpd.conf
Include conf files are under /etc/httpd/conf.d (depends on the location specified in main httpd)
Startup script for plesk apache /usr/local/psa/admin/bin/httpsdctl start
Apache main log files under /var/log/httpd

PHP

Php configuration file /etc/php.ini
Php extension modules are taken from /etc/php.d

Named

Conf file located /var/named/run-root/etc/named.conf
DB record /var/named/run-root/var/domain.com
Log file /var/log/messages
Service to restart /etc/init.d/named restart

FTP

Conf file /etc/proftpd.conf
Log file /var/log/messages

Mysql

Databases are located at /var/lib/mysql
Configuration file /etc/my.cnf
Mysql log /var/log/mysqld.log

Mail Server

Location of qmail directory /var/qmail
Mail directory of a domain /var/qmail/mailnames/domain.com
Mail log /var/log/maillog or /usr/local/psa/var/log/maillog

Domain

Home directory /var/www/vhosts/domain.com
Httpd conf file of a domain /var/www/vhosts/domain.com/conf/httpd.include
document root directory /var/www/vhosts/domain.com/httpdocs
Document root directory of secure website /var/www/vhosts/domain.com/httpdsdocs
Subdomains are created under /var/www/vhosts/domain.com/subdomains
Domain specific logs are under /var/www/vhosts/domain.com/statistics/logs