SET @start_global_value = @@global.ROCKSDB_DATADIR;
SELECT @start_global_value;
@start_global_value
./#rocksdb
"Trying to set variable @@global.ROCKSDB_DATADIR to 444. It should fail because it is readonly."
SET @@global.ROCKSDB_DATADIR   = 444;
ERROR HY000: Variable 'rocksdb_datadir' is a read only variable
