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--- centos_7_migration_notes [2021/05/03 18:10] – juckins
+++ centos_7_migration_notes [2025/03/20 19:58] (current) – ↷ Links adapted because of a move operation juckins
@@ Line 2: / Line 2: @@
 RHEL5/6/7 Cheatsheet: {{:rhel_5_6_7_cheatsheet_201410.pdf|}}
+[[https://tuxcare.com/extended-lifecycle-support/|Tuxcare's CentOS 7 Extended Support]]
+Dec 2023 (for Dell XPS 8930 tower):
+  * Updated kernel from kernel-3.10.0-1160.102.1.el7.x86_64 to kernel-3.10.0-1160.105.1.el7.x86_64
+  * Attempted to rebooted machine but after the BIOS splash screen, only got a blank screen with blinking cursor in upper-left corner
+  * Restarted machine using the power button but had same condition
+  * Restarted once again but at the BIOS splash screen selected F12
+  * For boot options, chose Boot from Hard Drive and list of kernels appeared
+  * Chose latest kernel and machine was OK
+  * After machine was running, did another restart and machine powered up with no issues
+Oct 2023 (for Dell XPS 8930 tower)
+  * Updated kernel from kernel-3.10.0-1160.99.1.el7.x86_64 to kernel-3.10.0-1160.102.1.el7.x86_64 and then machine would not boot, just blank screen with blinking cursor in upper-left corner
+  * Powered off machine, unplugged the USB peripheral cables
+  * Unplugged power cable for 30 seconds
+  * Rebooted and used F12 to go into BIOS Boot Options
+  * Tried to boot to Hard Drive but that immediately failed with error 'press any key to reboot'
+  * After that, the machine booted up OK and the normal selection of kernels appeared
 Other fixes:
@@ Line 13: / Line 33: @@
       * ''pymysql.err.OperationalError: (2003, "Can't connect to MySQL server on '127.0.0.1' ([Errno 99] Cannot assign requested address)")''
   * Updated /etc/my.cnf.d/server.cnf with this setting under [mariadb-5.5]
-      * ''max_connections = 800''
-  * ''systemctl restart mariadb.service''
+  max_connections = 818 (Note that 818 seems to be the absolute limit)
-  * Other commands to check status of mariadb server:
+  back_log = 1024 (Note that OS limit is in /proc/sys/net/ipv4/tcp_max_syn_backlog)
-      * ''set global max_connections = 800;''
+  thread_cache_size = 818
+  thread_handling = pool-of-threads
+Then do: ''systemctl restart mariadb.service''
+  * Other commands to check and modify on mariadb server:
       * ''show variables like "max_connections";''
-      * ''show global status like "Threads_connected"''
+      * ''show global status like "Threads_connected";''
+      * ''show status like "Conn%";''
+      * ''show status like "Threads%";''
+      * ''show global status;''
+  * See https://mariadb.com/kb/en/configuring-mariadb-for-optimal-performance/
   * Also check python3 coding best practices for opening/closing database connections
+    * I have noted that opening and closing the database connection only once in the python script helps reduce database "cannot assign requested address" errors
   * [[https://pypi.org/project/mysqlclient/|mysqlclient]] is supposedly [[https://stackoverflow.com/questions/43102442/whats-the-difference-between-mysqldb-mysqlclient-and-mysql-connector-python|faster than alternatives]]
       * import MySQLdb
@@ Line 405: / Line 435: @@
   * [[Yum installer bash script (CentOS7)|Copy this source to a .bash and run as root]]
-[[install_configure_cpan|CPAN packages]] to install:
+[[perl_install_configure_cpan|CPAN packages]] to install:
   * <color #ed1c24>NOTE</color>: Do not update .bashrc for library locations or else they will go into the wrong path
     * [[http://stackoverflow.com/questions/33636231/installed-cpan-modules-in-problematic-location|Wrong location of perl libraries]]
@@ Line 423: / Line 453: @@
     * Yet another option is to use modules that are in a repository
-[[http://www.if-not-true-then-false.com/2010/install-adobe-flash-player-10-on-fedora-centos-red-hat-rhel/|Ensure Adobe Flash plugin is installed]]
+<del>[[http://www.if-not-true-then-false.com/2010/install-adobe-flash-player-10-on-fedora-centos-red-hat-rhel/|Ensure Adobe Flash plugin is installed]]</del>
 [[http://www.cyberciti.biz/faq/howto-install-linux-apache-mariadb-php-lamp-stack-on-centos7-rhel7/|Ensure Apache is installed and running]]
@@ Line 430: / Line 460: @@
   * [[http://howtolamp.com/lamp/httpd/2.4/customizing/|Tips for users and permissions #2]]
-[[centos_php7.2_upgrade|Upgrade PHP to version 7.2]]
+<del>[[centos_php7.2_upgrade|Upgrade PHP to version 7.2]]</del>
+[[https://computingforgeeks.com/how-to-install-php-7-4-on-centos-7/|Upgrade PHP to version 7.4]]
 Migrate /etc/php.ini from old server and relax settings due to test env:
@@ Line 458: / Line 490: @@
 Database work:
+  * Update /etc/my.cnf.d/server.cnf with this setting under [mariadb-5.5]
+    * ''max_connections = 800''
+    * ''systemctl restart mariadb.service''
   * Backup /etc/my.cnf
     * Add this line under [mysqld]
@@ Line 480: / Line 515: @@
       * systemctl start mariadb.service
       * systemctl enable mariadb.service
-    * mysql DATABASE -h localhost -u USER -p'PASS' < /tmp/DATABASE.sql
+    * mysql -u USER -p'PASSWORD' (to login to mysql at command line)
+      * CREATE DATABASE database_name;
+      * Now logout of command line
+    * mysql DATABASE_NAME -h localhost -u USER -p'PASS' < /tmp/DATABASE.sql
   * Note CentOS7 comes with PHP 5.4 and latest version of phpMyAdmin that will work is 4.4.x