To achieve better performance, UNIX uses raw disk devices, and Windows NT uses unbuffered NTFS files to bypass the buffering of disk I/O that the operating system normally performs. To create raw devices on UNIX, follow the instructions provided with your operating system. To configure unbuffered NTFS files on Windows NT, follow the steps in the installation program.
Some operating systems use the concept of a logical volume, and others use a logical unit. Each of these terms represents the basic unit of physical disk space that the operating system reserves for the database server. A chunk is a physical partition, logical volume, a logical unit, or regular file that has been assigned to the database server. Use the onutil utility to create chunks on a coserver.