scu(8)scu(8)NAMEscu - SCSI CAM Utility Program
SYNOPSIS
/sbin/scu [-options ...] [command [keywords...]]
OPTIONS
Specifies the user agent path. Use an exclusive open. If you do not
specify this option, a device is closed after the scu utility obtains
its SCSI address information. Specify the raw device path name. You
must specify a character device special file, for example,
/dev/rdisk/dsk10c.
If the device name is not specified on the command line, the
program checks the environment variable SCU_DEVICE to define the
device name. Do not execute a startup script. Disable device
directory scanning. This is the default mode unless you specify
the -S option. Enable pipe operation mode. Specify a script
startup file name. Enable device directory scanning.
DESCRIPTION
The SCSI utility program, scu, interfaces with the CAM I/O subsystem
and the peripherals attached to the SCSI buses. Use this program to
maintain and diagnose problems with SCSI peripherals and the CAM I/O
subsystem.
Warning
Data corruption can occur when the write back cache is enabled using
the scu utility. Do not enable the write back cache.
If you enter the scu command without options it enters interactive
mode. The scu> prompt is displayed until you terminate the utility by
using the exit option. You can abbreviate options to the least unam‐
biguous number of characters. The following rules determine how the scu
utility initializes: If you do not specify a device name on the command
line, the scu utility defaults to the environment variable SCU_DEVICE,
providing that variable is defined. If you do not specify a
startup_file by using the -s option, the scu utility checks the
SCU_SCRIPT environment variable and if defined, uses the value of that
variable. If neither of the preceding conditions are true, the scu
utility checks for a initialization file, first in the current direc‐
tory and then in the user's $HOME path.
The device directory scanning option is disabled by default on Tru64
UNIX systems. You can set the environment variable SCU_DEVICE_SCANNING
{yes|no} to enable directory scanning. Directory scanning only occurs
during a scu show edt"command.
The scu utility program has an extensive help feature. Log in as root
and enter /sbin/scu help at the command prompt to view the help over‐
view and enter a ? at the topic> prompt to view a list of the util‐
ity's commands and conventions.
The file /sbin/scu.hlp contains the help information used in the help
feature.
Some common device maintenance tasks that you can perform by using the
scu utility are: Formatting disks, diskettes and optical media Scanning
media for bad blocks and reassigning bad blocks Verifying media (non-
destructively) Viewing device defect lists Downloading new firmware
Moving media in jukeboxes. Obtaining device information, such as prod‐
uct and vendor names, firmware revision, serial numbers, device capac‐
ity, block size, media type, and tape density
Some common diagnostic and test functions that you can perform by using
the scu utility are: Execute device diagnostics, such as self-tests
modify mode parameters Display log pages (such as error counters) Test
read/write media testing Test read/write controller memory Tape erase
or re-tensioning Generate hard or soft media errors Obtain performance
information CD-ROM audio operations Diagnose hardware problems
COMMANDS
The following table summarizes the scu commands and their functions.
Refer to the help command for complete syntax and examples of use.
──────────────────────────────────────────────────────────────────
Command Function
──────────────────────────────────────────────────────────────────
allow Allows media removal from a device
change Changes mode pages for a device
download Downloads microcode to a device
dump Dumps data from a device
eject Stops a CD-ROM and then ejects its caddy
erase Performs erase operations on a device
exit Exit the scu program. Ctrl/d can be used in interac‐
tive operation. An alias for exit is quit.
evaluate Evaluates an expression
format Formats disk media
help Displays help on scu command elements
mbad Produces hard and soft errors on disks
mt Issues one of the supported magnetic tape commands
onerror Controls program actions when an error occurs
pause Pauses playing a CD-ROM audio disk
play Plays tracks on a CD-ROM audio disk
prevent Prevents removal of media from a device
read Performs read operations on a device
reassign Reassigns a defective block on a disk device
release Releases a reserved device or a frozen SIM queue
repeat Defines a repeat count for a series of commands
reserve Reserves a device for exclusive use
resume Resumes playing a paused CD-ROM audio disk
reset Resets a bus or device
rezero Issues a CAM Bus Reset CCB command
scan Scans device media or the CAM Equipment Device Table
(EDT)
seek Seeks a logical block address
set Sets parameters for a device or the scu program
shell Exits to shell program until you exit the shell
show Displays parameters for a device or the scu program
sleep Specifies the time the scu program is to sleep
source Sources input from an external command file
start Starts a unit that is stopped
stop Stops a unit
switch Switches to another device
system Passes one system command to the shell program
test Performs tests on a controller
time Times command sequences
tur Issues a Test Unit Ready command to a device
usleep Specifies the time the scu program is to sleep (in
microseconds).
verify Performs verify operations on a device
write Performs write operations on a device
xza Performs operations on the KZMSA controller
zero Zeros device or scu program parameters
──────────────────────────────────────────────────────────────────
RESTRICTIONS
Commands that modify device data or device parameters require write
access to the device entry. Applications that change the volume level
of the CD-ROM must open the device for write access since a SCSI Mode
Select command is used to modify the volume level.
EXIT STATUS
Success. Warning. Failure.
ERRORS
When a SCSI device error occurs, both the sense key and the addition
sense code or qualifier are decoded and displayed as follows: scu:
Sense Key = 0x5 = ILLEGAL REQUEST - Illegal request or CDB parameter,
Sense Code/Qualifier = (0x20, 0) = Invalid command operation code
This error indicates that you have issued a command that is not sup‐
ported by the selected device. This can happen for optional commands
that are not supported by all devices.
EXAMPLES
To format an RX26 diskette at extra density, enter: scu> format density
ED To verify 1024 blocks starting at block 1000, enter: scu> verify
media starting 1000 length 1024 To display all changeable mode pages
for a device, enter: scu> show page pcf changeable To display inquiry
information for all devices on the first SCSI bus at lun 0 in the
Equipment Device Table (EDT), enter: scu> show edt bus 0 lun 0 full
FILES
The SCSI Utility executable file. The device entry for the CAM User
Agent driver. Contains the scu help information. Is the location of
the raw device special files for hard disk devices.
SEE ALSO
Commands: file(1), more(1)
Functions: open(2), close(2), ioctl(2), fopen(3), fgets(3), fputs(3),
popen(3), pclose(3), malloc(3), printf(3), fprintf(3)
American National Standard for Information Systems, Small Computer Sys‐
tems Interface - 2 (SCSI - 2), X3.131-199X
American National Standard for Information Systems, SCSI-2 Common
Access Method: Transport and SCSI Interface Module, working draft,
X3T9.2/90-186
scu(8)
