dspace discovery error with tomcat9 /dspace/solr/search/data/index/write.lock: Read-only file system

copy the tomcat9.service file to /etc/systemd/system 
cp /usr/lib/systemd/system/tomcat9.service /etc/systemd/system/

and modify
 it by adding

 ReadWritePaths=/dspace/solr/
 ReadWritePaths=/dspace/solr/search/data

 Then execute systemctl daemon-reload.