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scu(8)
NAME
scu - SCSI CAM Utility Program
SYNOPSIS
/sbin/scu [-options ...] [command [keywords...]]
OPTIONS
-c [cam-device]
Specifies the user agent path.
-e Use an exclusive open. If you do not specify this option, a device is
closed after the scu utility obtains its SCSI address information.
-f [device-name]
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.
-n Do not execute a startup script.
-N Disable device directory scanning. This is the default mode unless you
specify the -S option.
-p Enable pipe operation mode.
-s startup-file
Specify a script startup file name.
-S 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 unambiguous 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 .scurc initialization file, first in the current
directory 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 overview and
enter a ? at the topic> prompt to view a list of the utility'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 product and vendor names,
firmware revision, serial numbers, device capacity, 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
interactive 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
0 (Zero)
Success.
1 Warning.
-1 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 supported
by the selected device. This can happen for optional commands that are not
supported by all devices.
EXAMPLES
1. To format an RX26 diskette at extra density, enter:
scu> format density ED
2. To verify 1024 blocks starting at block 1000, enter:
scu> verify media starting 1000 length 1024
3. To display all changeable mode pages for a device, enter:
scu> show page pcf changeable
4. 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
/sbin/scu
The SCSI Utility executable file.
/dev/cam
The device entry for the CAM User Agent driver.
/sbin/scu.hlp
Contains the scu help information.
/dev/rdisk
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 Systems
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
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Index for
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Alphabetical
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