DB_BLOCK_SIZE specifies (in bytes) the size of Oracle database blocks. Range of values 2048 to 32768, but your operating system may have a narrower range The value for DB_BLOCK_SIZE in effect at the time you create the database determines the size of the blocks. The value must remain set to its initial value. For Oracle Real Application Clusters (Oracle RAC), this parameter affects the maximum value of the FREELISTS storage parameter for tables and indexes. Oracle uses one database block for each freelist group. Decision support system (DSS) and data warehouse database environments tend to benefit from larger block size values. Note:64-bit operating systems support a maximum DB_BLOCK_SIZE value of 32768