NAME

rl  − RL11/RL01 or RL02 disk

DESCRIPTION

The RL11 controller supports a mix of up to four RL01/RL02 disks. 

Refer to the ULTRIX-11 System Management Guide, Section 1.4 for more information about logical disk names and Appendix D for disk sizes. 

Rl# refers to an entire disk as a single sequentially-addressed file.  Its 256-word blocks are numbered 0 to 10239 (RL01) or 0 to 20479 (RL02).  The physical disk sector size is 128 words, however the logical block size is 256 words.  Minor device numbers are drive numbers on one controller. 

The rl files discussed above access the disk via the system’s normal buffering mechanism and may be read and written without regard to physical disk records. 

There is also a ’raw’ interface which provides for direct transmission between the disk and the user’s read or write buffer.  A single read or write call results in exactly one I/O operation and therefore raw I/O is considerably more efficient when many words are transmitted.  The names of the raw RL files begin with rrl and end with a number which selects the same disk as the corresponding rl file. 

In raw I/O the buffer must begin on a word boundary, and counts should be a multiple of 512 bytes (a disk block).  Likewise seek calls should specify a multiple of 512 bytes. 

FILES

/dev/rl#, /dev/rrl#

SEE ALSO

ULTRIX-11 System Management Guide, Section 2.6 and Appendix A
ULTRIX-11 Software Technical Description

RESTRICTIONS

In raw I/O read and write(2) truncate file offsets to 512-byte block boundaries, and write scribbles on the tail of incomplete blocks.  Thus, in programs that are likely to access raw devices, read, write and lseek(2) should always deal in 512-byte multiples.