Database Block Size 

Minimum  

2048 bytes; must be a multiple of operating system physical block size. 

Maximum 

Operating system dependent; never more than 32 KB. 

Database Blocks 

Minimum in initial extent of a segment. 

2 blocks 

Maximum per datafile 

Platform dependent; typically 2²²-1 blocks. 

Controlfiles 

Number of control files 

1 minimum; 2 or more (on separate devices) strongly recommended. 

Size of a control file 

Dependent on operating system and database creation options; maximum of 20,000 x (database block size). 

Database files 

Maximum per tablespace 

Operating system dependent; usually 1022. 

Maximum per database 

65533.

May be less on some operating systems.

Limited also by size of database blocks and by the DB_FILES initialization parameter for a particular instance. 

Database extents 

Maximum 

2 GB, regardless of the maximum file size allowed by the operating system. 

Database file size 

Maximum 

Operating system dependent. Limited by maximum operating system file size; typically 2²² or 4M blocks. 

MAXEXTENTS 

Default value 

Derived from tablespace default storage or DB_BLOCK_SIZE initialization parameter. 

Maximum 

Unlimited 

Redo Log Files 

Maximum number of logfiles 

Limited by value of LOG_FILES initialization parameter or MAXLOGFILES parameter in the CREATE DATABASE statement.

Control file can be resized to allow more entries; ultimately an operating system limit. 

Maximum number of logfiles per group 

Unlimited 

Redo Log File Size 

Minimum size 

50K bytes 

Maximum size 

Operating system limit; typically 2GB. 

Tablespaces 

Maximum number per database 

64K

Number of tablespaces cannot exceed the number of database files, as each tablespace must include at least one file.