HK(4)

NAME
hk - RK6-11/RK06 and RK07 moving head disk

SYNOPSIS
/sys/conf/SYSTEM:
	NHK	hk_drives	# RK611, RK06/07
/etc/dtab:
	#Name	Unit#	Addr	Vector	Br	Handler(s)		# Comments
	hk	?	177440	210	5	hkintr		# rk611/711 rk06/07
major device number(s):
	raw: 13
	block: 4
minor device encoding:
	bits 0007 specify partition of HK drive
	bits 0070 specify HK drive

DESCRIPTION
Files with minor device numbers 0 through 7 refer to various portions of drive 0; minor devices 8 through 15 refer to drive 1, etc. The standard device names begin with ``hk'' followed by the drive number and then a letter a-h for partitions 0-7 respectively. The character ? stands here for a drive number in the range 0-7.

The block files 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 files conventionally begin with an extra `r.'

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

DISK SUPPORT
Disks must be labeled using either the standalone disklabel program on the boot tape or with the disklabel(8) program. There are no partition tables coded into the hk drivers, these must be placed on the drive with disklabel.

Traditionally the hk?a partition is used for the root filesystem, the b partition as a swap area and the c partition for disk to disk copying (it spans the entire disk).

The kernel uses the c partition to access the bad block information stored at the end of some packs. Extreme care must be taken when creating file systems on this partition to avoid overwriting any bad block information present. User data should use the h partition which should be at least one track (one cylinder might be best) shorter than the c partition.

FILES
/dev/hk[0-7][a-h]    block files
/dev/rhk[0-7][a-h]    raw files
/dev/MAKEDEV    script to create special files
/dev/MAKEDEV.local    script to localize special files

SEE ALSO
ra(4) ram(4), rk(4), rl(4), rx(4), si(4), xp(4), dtab(5), autoconfig(8), disklabel(8)

DIAGNOSTICS
hk%d%c: hard error sn%d cs2=%b ds=%b er=%b. An unrecoverable error occurred during transfer of the specified sector of the specified disk partition. The contents of the cs2, ds and er registers are printed in octal and symbolically with bits decoded. The error was either unrecoverable, or a large number of retry attempts (including offset positioning and drive recalibration) could not recover the error.

hk%d: write locked. The write protect switch was set on the drive when a write was attempted. The write operation is not recoverable.

hk%d: not ready. The drive was spun down or off line when it was accessed. The i/o operation is not recoverable.

hk%d: not ready (came back!). The drive was not ready, but after printing the message about being not ready (which takes a fraction of a second) was ready. The operation is recovered if no further errors occur.

hk%d%c: soft ecc sn%d. A recoverable ECC error occurred on the specified sector of the specified disk partition. This happens normally a few times a week. If it happens more frequently than this the sectors where the errors are occuring should be checked to see if certain cylinders on the pack, spots on the carriage of the drive or heads are indicated.

BUGS
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.

DEC-standard error logging should be supported.

A program to analyze the logged error information (even in its present reduced form) is needed.