To allocate raw space, you must have a disk partition available that is dedicated to raw space. To create raw disk space, you can either repartition your disks or unmount an existing file system. Back up any files before you unmount the device.
For specific instructions on how to allocate raw disk space on UNIX, see your operating-system documentation and Unbuffered or Buffered Disk Access on UNIX.
The filename of the character-special device usually begins with the letter r. For the procedure, see steps 4 and 5 in Allocating Cooked File Spaces on UNIX.