scsictl - control a SCSI device
scsictl [-akq] [-c command]... [-m mode[=value]]... device
The scsictl command provides a mechanism for controlling a SCSI
device. It can be used to query mode parameters, set configurable
mode parameters, and perform SCSI commands. The operations are
performed in the same order as they appear on the command line.
device specifies the character special file to use.
scsictl recognizes the following options.
-a Display the status of all mode parameters available,
separated by semicolon-blank (; ) or newline.
Cause the device to perform the specified command.
command can be one of the following:
erase For magneto-optical devices that support
write without erase, this command can be used
to pre-erase the whole surface to increase
data throughput on subsequent write
operations. This command maintains exclusive
access to the surface during the pre-erasure.
For devices that have an internal write
cache, this command causes the device to
flush its cache to the physical medium.
-k Continue processing arguments even after an error is
detected. The default behavior is to exit immediately
when an error is detected.
Command line syntax is always verified for correctness,
regardless of the -k option. Improper command line
syntax causes scsictl to exit without performing any
operations on the device.
-m mode Display the status of the specified mode parameter.
mode can be one of the following:
For devices that support immediate reporting,
this mode controls how the device responds to
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write requests. If immediate report is
enabled (1), write requests can be
acknowledged before the data is physically
transferred to the media. If immediate
report is disabled (0), the device is forced
to await the completion of any write request
before reporting its status.
ir Equivalent to immediate_report.
For devices that support a queue depth
greater than the system default, this mode
controls how many I/Os the driver will
attempt to queue to the device at any one
time. Valid values are (1-255). Some disk
devices will not support the maximum queue
depth settable by this command. Setting the
queue depth in software to a value larger
than the disk can handle will result in I/Os
being held off once a QUEUE FULL condition
exists on the disk.
Set the mode parameter mode to value. The available
mode parameters and values are listed above.
Mode parameters that take only a binary value (1 or 0)
can also be specified as either on or off,
-q Suppress the labels that are normally printed when mode
parameters are displayed. Mode parameter values are
printed in the same order as they appear on the command
line, separated by semicolon-blank (; ) or newline.
Mode parameters and commands need only be specified up to a unique
prefix. When abbreviating a mode parameter or command, at least the
first three characters must be supplied.
Diagnostic messages are generally self-explanatory.
To display all the mode parameters, turn immediate_report on, and
redisplay the value of immediate_report:
scsictl -a -m ir=1 -m ir /dev/rdsk/c0t6d0
producing the following output:
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immediate_report = 0; queue_depth = 8; immediate_report = 1
The same operation with labels suppressed:
scsictl -aq -m ir=1 -m ir /dev/rdsk/c0t6d0
produces the following output:
0; 8; 1
Not all devices support all mode parameters and commands listed above.
Changing a mode parameter may have no effect on such a device.
Issuing a command that is not supported by a device can cause an error
message to be generated.
scsictl is not supported on sequential-access devices using the tape
The immediate_report mode applies to the entire device; the section
number of the device argument is ignored.
To aid recovery, immediate reporting is not used for writes of file
system data structures that are maintained by the operating system,
writes to a hard disk (but not a magneto-optical device) through the
character-device interface, or writes to regular files that the user
has made synchronous with O_SYNC or O_DSYNC (see open(2) and
When the system is rebooted, the disc3 driver always resets the value
of the immediate_report mode parameter to off. If ioctl() or scsictl
is used to change the setting of immediate reporting on a SCSI device,
the new value becomes the default setting upon subsequent
configuration (e.g., opens) of this device and retains its value
across system or device powerfail recovery. However, on the next
system reboot, the immediate-report mode parameter is again reset to
the value of the tunable system parameter, default_disk_ir. This is
set in the system_file used to create the HP-UX system by the config
command (see config(1M)).
If ioctl() or scsictl is used to change the setting of immediate
reporting on a SCSI device, the new value becomes the default setting
upon subsequent configuration (e.g., opens) of this device until the
"last close" of the device, that is, when neither the system nor any
application has the device open (for example, unmounting a file system
via umount and then mounting it again via mount (see mount(1M)). On
the next "first open", the immediate-report mode parameter is again
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reset to the value of the tunable system parameter, default_disk_ir.
This is set in the system_file used to create the HP-UX system by the
config command (see config(1M)).
config(1M), diskinfo(1M), fcntl(2), open(2).
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