MariaDB server cannot start.
The following error is found in
[ERROR] InnoDB: redo log file './ib_logfile1' exists. Creating system tablespace with existing redo log files is not recommended. Please delete all redo log files before creating new system tablespace.
Obsolete redo log file preventing MariaDB from operating correctly.
Connect to the server via SSH.
# mv /var/lib/mysql/ib_logfile* /root/
# systemctl start mariadb