Debug mysqld - mariadb galera server

1 - Debug mysqld server

mysqladmin status
service mysql status
service mysqld status
ps -ef | grep mysqld | grep -v grep
mysql -uroot -p -A -e"SHOW VARIABLES;" > MySQLCurrentSettings.txt
tail -f /var/log/mysqld/mysql_error.log
tail -f /var/log/mysqld/mysql_slow.log
pt-summary
pt-mysql-summary --user=root --ask-pass
pt-variable-advisor localhost --user=root --ask-pass
pt-query-digest
explain
profiling
perl mysqltuner.pl
mysql> show engine innodb status\G
mysql> show full processlist\g
mysql> show global status like '%Threads_running%';
mysql> show global status like '%Threads_cached%';
mysql> show global variables like '%read_only%';
mysql> show engine innodb status\G
mysql> show slave hosts\G
mysql> show slave status\G
atop
iotop
systemctl firewalld status
service iptables status
systemctl status ntp.service
iptables -L -n -v
sestatus
ethtool <interface>
ncdu
df -Th
ps aux | awk '{if ($8 ~ "D") print $0}'
ps aux | awk '{if ($8 ~ "Z") print $0}'
w
top
cat /proc/`pidof <processname>`/limits | egrep '(processes|files)'
dmesg
tail -f /var/log/message
nethogs <interface>
iftop -i <interface>
ss -s
lsof -i :<port>
netstat -anp | grep -i mysql

2 - Debug mariadb galera server

Include check mysqld server and add more:

lsof -i :4567
cat /var/lib/mysql/grastate.dat
tail -f /var/lib/mysql/innobackup.backup.log
netstat -anp | grep -i mysql
mysql> show global status like '%wsrep_cluster_size%';
mysql> show global status like '%wsrep_cluster_status%';
mysql> show global status like '%wsrep_cluster_state_uuid%';
mysql> show global status like '%wsrep_local_state_uuid%';
mysql> show global status like '%wsrep_incoming_addresses%';
mysql> show global status like '%wsrep_connected%';
mysql> show global status like '%wsrep_ready%';
mysql> show global status like '%wsrep_local_state_comment%';
mysql> show global status like '%wsrep_local_recv_queue%';
mysql> show global status like '%wsrep_local_recv_queue_avg%';
mysql> show global status like '%wsrep_local_send_queue%';
mysql> show global status like '%wsrep_local_send_queue_avg%';
mysql> show global status like '%wsrep_flow_control_paused%';
mysql> show global status like '%wsrep_flow_control_sent%';
mysql> show global status like '%wsrep_flow_control_recv%';