Follow guide available at iUS

systemctl stop mariadb
yum install yum-plugin-replace
yum replace mariadb-server --replace-with mariadb101u-server

File limit require to upgrade mariadb.

mkdir /etc/systemd/system/mariadb.service.d

/etc/systemd/system/mariadb.service.d/limit.conf

[Service]
LimitNOFILE=320000

systemctl start mariadb

mysqlcheck --no-defaults --check-upgrade --auto-repair --databases mysql -p
mysqlcheck --no-defaults --check-upgrade --all-databases --auto-repair --write-binlog -p
mysqlcheck --no-defaults --all-databases --fix-db-names --fix-table-names --write-binlog -p
mysql_upgrade