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 scsictl(1M)							 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



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 scsictl(1M)							 scsictl(1M)




			       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:




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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

 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



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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)).

 SEE ALSO
      config(1M), diskinfo(1M), fcntl(2), open(2).
















































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