SCUZZ(8) SCUZZ(8)
NAME
scuzz - SCSI target control
SYNOPSIS
scuzz [ -6eq ] [ -m max-xfer ] [ [ -r ] sddev ]
DESCRIPTION
Scuzz is an interactive program for exercising raw SCSI
devices. Its intended purpose is to investigate and manipu-
late odd devices without the effort of writing a special
driver, such as shuffling the media around on an optical
jukebox. It reads commands from standard input and applies
them to a SCSI target (other devices accessed through the
sd(3) interface, such as ATA(PI) devices, may also work).
If sddev is given on the command line, an open (see below)
is immediately applied to the target. On successful comple-
tion of a command, ok n is printed, where n is the number of
bytes transferred to/from the target; the -q command line
option suppresses the ok message.
The -6 forces the use of 6-byte SCSI commands rather than
10-byte ones. Some older devices require this, though scuzz
attempts to adapt automatically. The -e makes scuzz more
willing to retry I/O errors but less tolerant of other
errors and implies -6. This option is often needed to read
Exabyte 8mm tapes. The -m option sets the maximum I/O
transfer size to max-xfer. Exabyte drives often require this
to be 1024 or the exact tape block size and some 4mm drives
require this to be the exact tape block size or larger.
Commands
help command
Help is rudimentary and prints a one line synopsis
for the named command, or for all commands if no
argument is given.
probe Probe attempts an inquiry command on all SCSI
units, and prints the result preceded by the name
of those targets which respond.
The help and probe commands may be given at any time.
open [-r]sddev
Open must be given before any of the remaining com-
mands will be accepted. Internally, unless the -r
option is given, open issues ready then inquiry,
followed by a device class-specific command to
determine the logical block size of the target.
Sddev is an sd(3) device directory like /dev/sdC0.
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close Close need only be given if another target is to be
opened in the current session.
The remaining commands are in rough groups, intended for
specific classes of device. With the exception of the read,
write, and space commands, all arguments are in the style of
ANSI-C integer constants.
ready Test Unit Ready checks if the unit is powered up
and ready to do read and write commands.
rezero Rezero Unit requests that a disk be brought to a
known state, usually by seeking to track zero.
rewind Rewind positions a tape at the beginning of current
partition (there is usually only one partition, the
beginning of tape).
reqsense Request Sense retrieves Sense Data concerning an
error or other condition and is usually issued fol-
lowing the completion of a command that had check-
condition status. Scuzz automatically issues a
reqsense in response to a check-condition status
and prints the result.
format Format Unit performs a ``low level'' format of a
disk.
rblimits Read Block Limits reports the possible block
lengths for the logical unit. Tapes only.
read file nbytes
Read transfers data from the target to the host. A
missing nbytes causes the entire device to be read.
write file nbytes
Write transfers data from the host to the target.
A missing nbytes causes the entire input file to be
transferred.
The first argument to the read and write commands
specifies a source (write) or destination (read)
for the I/O. The argument is either a plain file
name or | followed by a command to be executed by
rc(1). The argument may be quoted in the style of
rc(1).
seek offset whence
Seek requests the target to seek to a position on a
disk, arguments being in the style of seek(2);
whence is 0 by default.
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Scuzz maintains an internal notion of where the
current target is positioned. The seek, read,
write, rewind, rezero, and wtrack commands all
manipulate the internal offset.
filemark howmany
Write Filemarks writes one (default) or more file-
marks on a tape.
space [-b] [-f] [[--]howmany]
Space positions a tape forwards or backwards. The
arguments specify logical block (-b) or filemark
(-f) spacing; default is -b. If howmany is nega-
tive it specifies spacing backwards, and should be
preceded by -- to turn off any further option pro-
cessing. Default is 1.
inquiry Inquiry is issued to determine the device type of a
particular target, and to determine some basic
information about the implemented options and the
product name.
modeselectbytes...
modeselect6bytes...
Mode Select is issued to set variable parameters in
the target. Bytes given as arguments comprise all
the data for the target; see an appropriate manual
for the format. The default is the 10-byte form of
the command; modeselect6 is the 6-byte version.
modesense [page[nbytes]]
modesense6 [page[nbytes]]
Mode Sense reports variable and fixed parameters
from the target. If no page is given, all pages
are returned. Nbytes specifies how many bytes
should be returned. The default is the 10-byte
form of the command; modesense6 is the 6-byte ver-
sion.
start [code]
stop [code]
eject [code]
ingest [code]
Start, stop, eject, and ingest are synonyms for
Start/Stop Unit with different default values of
code. Start/Stop Unit is typically used to spin up
and spin down a rotating disk drive. Code is 0 to
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stop, 1 to start and 3 to eject (if the device sup-
ports ejection of the medium).
capacity Read Capacity reports the number of blocks and the
block size of a disk.
The following commands are specific to CD and CD-R/RW
devices. A brief description of each is given; see the
SCSI-3 Multimedia Commands (MMC) Specification for details
of arguments and interpretation of the results.
blank [track/LBA[type]]
Erase a CD-RW disk. Type identifies the method and
coverage of the blanking.
rtoc [track/session-number[ses]]
The Read TOC/PMA command transfers data from one of
the tables of contents (TOC or PMA) on the CD
medium.
rdiscinfo
(Note the spelling.) Provides information about
disks, including incomplete CD-R/RW.
rtrackinfo [track]
Provides information about a track, regardless of
its status.
cdpause
cdresume Pause/resume playback.
cdstop Stop playback.
cdplay [track-number] or [-r[LBA[length]]]
Play audio. With no arguments, starts at the
beginning of the medium. If a track number is
given, the table of contents is read to find the
playback start point. If the -r option is given,
block addressing is used to find the playback start
point.
cdload [slot]
cdunload [slot]
Load/unload a disk from a changer.
cdstatus Read the mechanism status.
The following commands are specific to Media Changer
devices. A brief description of each is given; see the
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SCSI-3 Medium Changer Commands (SMC) Specification for
details of arguments.
einit Initialize element status.
estatus type [length]
Report the status of the internal elements. Type 0
reports all element types.
mmove transport source destination[invert]
Move medium.
FILES
/dev/sdXX/raw raw SCSI interface for command, I/O, and sta-
tus.
SOURCE
/sys/src/cmd/scuzz
SEE ALSO
sd(3)
Small Computer System Interface - 2 (X3T9.2/86-109), .}f
Global Engineering Documents
SCSI Bench Reference, ENDL Publications
SCSI-3 Multimedia Commands (MMC) Specification, www.t10.org
SCSI-3 Medium Changer Commands (SMC) Specification, .}f
www.t10.org
BUGS
Only a limited subset of SCSI commands has been implemented
(as needed).
Only one target can be open at a time.
LUNs other than 0 are not supported.
No way to force 10-byte commands, though they are the
default.
Should be recoded to use scsi(2) in order to get more com-
plete sense code descriptions.
Scuzz betrays its origins by spelling rdiscinfo with a c
even though the devices it manipulates are spelled with a k.
The max-xfer value is currently limited to 245760 to limit
kernel memory consumption.
It may be necessary to set max-xfer to exactly the block
size used to write a tape in order to read it on some
drives.
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