scsictl(1M)

NAME

scsictl — control a SCSI device

SYNOPSIS

scsictl [-akq] [-c command]... [-m mode[= value]]... device

DESCRIPTION

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.

Options

scsictl recognizes the following options.

-a

Display the status of all mode parameters available, separated by semicolon-blank (; ) or newline.

-c command

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.
sync_cache: 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:

immediate_report: For devices that support immediate reporting, this mode controls how the device responds to 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.
queue_depth: 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.

-m mode=value

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, respectively.

-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.

DIAGNOSTICS

Diagnostic messages are generally self-explanatory.

EXAMPLES

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:

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 

WARNINGS

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 driver.

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 fcntl(2)).

DEPENDENCIES

disc3

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)).

sdisk

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 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)).