Create a raw datafile Two key points: 1. Use /dev/rdsk not /dev/dsk (actually I think all operations except mount use raw disks) 2. Say REUSE in CREATE TABLESPACE #format p p and create / make sure there is a free partition (free so it's not shown in df -kl) say it shows: partition> p Current partition table (original): Total disk cylinders available: 7506 + 2 (reserved cylinders) Part Tag Flag Cylinders Size Blocks 0 unassigned wm 0 - 1869 4.20GB (1870/0/0) 8811440 1 unassigned wm 1870 - 3739 4.20GB (1870/0/0) 8811440 2 backup wu 0 - 7505 16.86GB (7506/0/0) 35368272 3 unassigned wm 3740 - 5609 4.20GB (1870/0/0) 8811440 4 unassigned wm 5610 - 5623 32.21MB (14/0/0) 65968 and df -kl | grep c0t1d0s3 doesn't return anything. Then # ls -l /dev/rdsk/c0t1d0s3 lrwxrwxrwx 1 root root 55 Jan 9 2002 /dev/rdsk/c0t1d0s3 -> ../../devices/sbus@1f,0/SUNW,fas@e,8800000/sd@1,0:d,raw # ls -l /devices/sbus@1f,0/SUNW,fas@e,8800000/sd@1,0:d,raw crw-r----- 1 root sys 32, 11 Jan 9 2002 /devices/sbus@1f,0/SUNW,fas@e,8800000/sd@1,0:d,raw # chown oracle:dba /devices/sbus@1f,0/SUNW,fas@e,8800000/sd@1,0:d,raw # cd /dev/rdsk # mkdir tiny; cd tiny #this way we put the files in the instance name directory # ln -s /dev/rdsk/c0t1d0s3 rawtest01.dbf In sqlplus, create a file slightly smaller than the partition (only 10m here for testing purpose): SQL> create tablespace rawtest datafile '/dev/rdsk/tiny/rawtest01.dbf' size 10304k reuse extent management local uniform size 64k; Tablespace created. The best size is 2*db_block_size smaller than partition size for a datafile, and 1*log block size smaller for log files.