Copyright (c) 1980 Regents of the University of California.
All rights reserved. The Berkeley software License Agreement
specifies the terms and conditions for redistribution.

@(#)uda.4 6.1 (Berkeley) 05/15/85

C 4 uda - UDA-50 disk controller interface "controller uda0 at uba0 csr 0172150 vector udaintr"

"disk ra0 at uda0 drive 0"

This is a driver for the DEC UDA-50 disk controller. The UDA-50 communicates with the host through a packet oriented protocol termed the Mass Storage Control Protocol (MSCP). Consult the file < vax/mscp.h > for a detailed description of this protocol.

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 ``ra'' 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 counts should be a multiple of 512 bytes (a disk sector). Likewise seek calls should specify a multiple of 512 bytes.

This driver handles all drives which may be connected to the UDA-50. Drive types per se are not recognized, but rather the variable length partitions are defined as having an ``infinite'' length and the controller is relied on to return an error when an inaccessible block is requested. For constructing file systems, however the partitions sizes are required. The origin and size (in sectors) of the pseudo-disks on each drive are shown below. Partitions are not rounded to cylinder boundaries, as on other drives, because the type of drive attached to the controller is discovered too late in the autoconfiguration process to maintain separate partition tables for each drive. (The lack of proper drive type recognition would be more easily dealt with if the partition tables were read off the drive.)

RA60 partitions
 disk start length
 ra?a 0 15884
 ra?b 15884 33440
 ra?c 0 400176
 ra?g 49324 82080
 ra?h 131404 268772

RA80 partitions
 disk start length
 ra?a 0 15884
 ra?b 15884 33440
 ra?c 0 242606
 ra?g 49324 82080
 ra?h 131404 111202

RA81 partitions
 disk start length
 ra?a 0 15884
 ra?b 15884 33440
 ra?c 0 891072
 ra?d 340670 15884
 ra?e 356554 55936
 ra?f 412490 478582
 ra?g 49324 82080
 ra?h 131404 759668

The ra?a partition is normally used for the root file system, the ra?b partition as a paging area, and the ra?c partition for pack-pack copying (it maps the entire disk).

/dev/ra[0-9][a-f]

/dev/rra[0-9][a-f]

"uda: ubinfo %x" . (VAX 11/750 only.) When allocating UNIBUS resources, the driver found it already had resources previously allocated. This indicates a bug in the driver.

"udasa %o, state %d" . (Additional status information given after a hard i/o error.) The values of the UDA-50 status register and the internal driver state are printed.

"uda%d: random interrupt ignored" . An unexpected interrupt was received (e.g. when no i/o was pending). The interrupt is ignored.

"uda%d: interrupt in unknown state %d ignored" . An interrupt was received when the driver was in an unknown internal state. Indicates a hardware problem or a driver bug.

"uda%d: fatal error (%o)" . The UDA-50 indicated a ``fatal error'' in the status returned to the host. The contents of the status register are displayed.

OFFLINE . (Additional status information given after a hard i/o error.) A hard i/o error occurred because the drive was not on-line.

"status %o" . (Additional status information given after a hard i/o error.) The status information returned from the UDA-50 is tacked onto the end of the hard error message printed on the console.

"uda: unknown packet" . An MSCP packet of unknown type was received from the UDA-50. Check the cabling to the controller.

The following errors are interpretations of MSCP error messages returned by the UDA-50 to the host.

"uda%d: %s error, controller error, event 0%o" .

"uda%d: %s error, host memory access error, event 0%o, addr 0%o" .

"uda%d: %s error, disk transfer error, unit %d" .

"uda%d: %s error, SDI error, unit %d, event 0%o" .

"uda%d: %s error, small disk error, unit %d, event 0%o, cyl %d" .

"uda%d: %s error, unknown error, unit %d, format 0%o, event 0%o" .

The partition tables are so poorly laid out that they almost certainly force each site to tailor them to their individual needs. The problem is even worse when a site has a mixed collection of drives. The best solution would be to read the partition tables off the drive.