scsimgr_esdisk(7)					 Miscellaneous Information Manual					 scsimgr_esdisk(7)

NAME

       scsimgr_esdisk - SCSI class driver esdisk plug-in for scsimgr

DESCRIPTION

       The  SCSI  class driver plug-in for implements management and diagnostic operations specific to classes of devices bound to the driver.	is
       the native HP-UX SCSI class driver that handles, by default, all block devices including the following types: direct access, CD/DVD, write-
       once read-multiple (WORM), and optical memory (OM).

       The plug-in handles the following operations for driver

	 o  Displays  and  clears  driver  global  statistics and the statistics it maintains on instances of LUNs bound to it, and on related LUN
	    paths.

	 o  Displays status and other information maintained by driver on LUNs bound to it.

	 o  Gets, sets, and saves driver global, per-lun instance attributes or attributes for a set of devices bound to the driver.

   Commands
       The user can explicitly send the following commands to driver plug-in by specifying the option:

	  Clears statistics.

	  Displays information on attributes.

	  Displays status and other information.

	  Displays statistics.

	  Saves value of attributes in a persistent store.

	  Set current values of attributes.

       Refer to scsimgr(1M) for the syntax of the above commands.

       However, the only instance when it is necessary to explicitly send a command to the plug-in is when performing operations on objects global
       to  driver  global  statistics, attributes or status information.  In all the other cases, automatically invokes the plug-in to perform the
       driver specific part of the operation, when the operation applies to LUNs bound to driver or to their LUN paths.

   Attributes
       The following table lists driver specific attributes.  Under the category "Device Set", the table lists which attributes the driver  allows
       at a settable attribute scope (also known as Device Data Repository, DDR).  Attribute scopes supported by are peripheral device type (pdt),
       vendor identifier (vid), product identifier (pid), and product revision (rev).  See attr_scope in scsimgr(1M) for more information.

       The following conventions are used :

	 o  RO is Read Only.

	 o  RW is Read Write.

	 o  uint32 is unsigned 32 bit integer.

	 o  Range of values for applicable attributes is listed.

       ------------------------------------------------------------------------------
       Object	   Attribute Name	RO/RW  Type	Description
       ------------------------------------------------------------------------------
       Global	   version		RO     string	Version of driver esdisk.
       ------------------------------------------------------------------------------
       LUN	   capacity		RO     uint32	Device capacity in number of
							blocks.
       ------------------------------------------------------------------------------

		   congest_max_retries	RW     uint32	Number of retries for device
							discovery I/Os	during	Busy
							or Queue Full condition.
							Range: 0 - 0xFFFFFFFF
       ------------------------------------------------------------------------------
		   block_size		RO     uint32	Block size in bytes.
       ------------------------------------------------------------------------------
		   format_secs		RW     uint32	Timeout  in  seconds of SCSI
							command FORMAT.
							Range: 0 - 0xFFFFFFFF
       ------------------------------------------------------------------------------
		   start_unit_secs	RW     uint32	Timeout in seconds  of	SCSI
							command START UNIT.
							Range: 0 - 0xFFFFFFFF
       ------------------------------------------------------------------------------
		   max_retries		RW     uint32	Maximum    number   of	 I/O
							retries.
							Range: 1 - 0xFFFFFFFF
       ------------------------------------------------------------------------------
		   path_fail_secs	RW     uint32	Timeout  in  seconds  before
							declaring  a  LUN  path off-
							line.
							Range: 0 - 0xFFFFFFFE
       ------------------------------------------------------------------------------
		   esd_secs		RW     uint32	Maximum time in seconds  for
							the transmission of an I/O.
							Range: 0 - 0xFFFFFFFF
       ------------------------------------------------------------------------------
		   load_bal_policy	RW     string	I/O load balancing policy.
							May be:
							round_robin
							least_cmd_load
							cl_round_robin
							closest_path
							preferred_path
							pref_tport
							weighted_rr
       ------------------------------------------------------------------------------
		   infinite_retries	RW     boolean	Enable or  disable  infinite
		   _enable				retry of I/Os.
							May be:
							true(1): enable
							false(0): disable
       ------------------------------------------------------------------------------

		   disable_flags	RW     string	A  set of flags representing
							SCSI  task  management	 and
							other  functions.  If a flag
							is  set,  the  corresponding
							function is disabled for the
							LUN.   The  following  flags
							are currently defined:
							WCE: Write Cache Enable
							RW16:  16  bytes  READ/WRITE
							CDB
							ABT:  SCSI  task  management
							function Abort Task Set
							CTS:  SCSI  task  management
							function Clear Task Set
							LR:  SCSI  task   management
							function LUN Reset
							WTR:  SCSI  task  management
							function Warm Target Reset
							CTR:  SCSI  task  management
							function Cold Target Reset
							BR: Bus Reset
							PR: Persistent Reservation
							WERO: Write Exclusive Regis-
							trants	  Only	  Persistent
							Reservation
							EARO:  Exclusive Access Reg-
							istrants   Only   Persistent
							Reservation
							ALL: Disable all functions
							NONE: Enable all functions
       ------------------------------------------------------------------------------
		   preferred_path	RW     string	Hardware  path, or class and
							instance number of  the  LUN
							path  to  use preferably for
							I/O transfer, when I/O	load
							balancing  policy  is set to
							preferred_path.
       ------------------------------------------------------------------------------
		   pref_tport		RW     string	Worldwide  name   (WWN)   in
							hexadecimal  of  the  target
							port to use  preferably  for
							I/O  transfer, when I/O load
							balancing policy is  set  to
							pref_tport.
       ------------------------------------------------------------------------------
		   alua_enabled 	RW     boolean	Indicates whether Asymmetric
							Logical Unit  Access  (ALUA)
							functionality is enabled for
							the LUN instance.  The value
							of  true(1) indicates that
							ALUA functionality  is	han-
							dled  if  LUN  supports  it.
							The value of false(0) indi-
							cates  that ALUA functional-
							ity is ignored even  if  LUN
							supports it.
							May be:
							true(1): enable ALUA
							false(0): disable ALUA
       ------------------------------------------------------------------------------

		   retry_delay		RW     boolean	Enables or disables  support
		   _enabled				of  retry  delay timer codes
							returned by devices  comply-
							ing  with SAM-4 (SCSI Archi-
							tecture Model 4), in case of
							congestion.  If set to false(0), retry delay timer codes
							are ignored.  If set to true(1), retry delay timer codes
							are  taken  into  considera-
							tion, when handling  conges-
							tion.
							May be:
							true(1): enable retry delay
							timer codes.
							false(0):  disable  disable
							retry timer codes.
       ------------------------------------------------------------------------------
		   ping_type		RW     string	Failed LUN path connectivity
							test.	Determines   whether
							the  system should automati-
							cally test the	connectivity
							of  a failed LUN path and if
							so which kind of  test	must
							be performed.
							May be set to:
							No  connectivity test should
							be performed.
							Basic	connectivity	test
							including    the    Standard
							Inquiry command,  should  be
							performed.
							Extended  connectivity	test
							including  Standard  Inquiry
							and  Test  Unit  Ready (TUR)
							commands  should   be	per-
							formed.
       ------------------------------------------------------------------------------
		   ping_recovery	RW     string	Failed	 LUN  path  recovery
							policy.  Determines  when  a
							failed	LUN  path  should be
							considered back online	when
							automatic  connectivity test
							is enabled.
							May be set to:
							Upon a successful connectiv-
							ity test.
							After  a  number of consecu-
							tive successful connectivity
							tests	specified   by	 the
							attribute
							Upon  sustained   successful
							connectivity   tests  within
							the time period specified in
							the attribute
       ------------------------------------------------------------------------------
		   ping_time  _thresh-	RW     uint32	Minimum time in seconds,  of
		   old					sustained successful connec-
							tivity tests before a failed
							LUN  path is considered back
							online.
							Range: 0 - 0xFFFFFFFF
       ------------------------------------------------------------------------------

		   ping_count _thresh-	RW     uint32	Minimum  number  of consecu-
		   old					tive successful connectivity
							tests  before  a  failed LUN
							path  is   considered	back
							online.
							Range: 0 - 0xFFFFFFFF
       ------------------------------------------------------------------------------
       Device Set  transient_secs	RW     uint32	Seconds  to wait after a LUN
							transitioned out  of  ONLINE
							state before failing I/Os.
							Range: 0 - 0xFFFFFFFE
       ------------------------------------------------------------------------------
		   congest_max_retries	RW     uint32	Number of retries for device
							discovery I/Os	during	Busy
							or Queue Full condition.
							Range: 0 - 0xFFFFFFFF
       ------------------------------------------------------------------------------
		   format_secs		RW     uint32	Timeout  in  seconds of SCSI
							command FORMAT.
							Range: 0 - 0xFFFFFFFF
       ------------------------------------------------------------------------------
		   start_unit_secs	RW     uint32	Timeout in seconds  of	SCSI
							command START UNIT.
							Range: 0 - 0xFFFFFFFF
       ------------------------------------------------------------------------------
		   max_retries		RW     uint32	Maximum    number   of	 I/O
							retries.
							Range: 1 - 0xFFFFFFFF
       ------------------------------------------------------------------------------
		   path_fail_secs	RW     uint32	Timeout  in  seconds  before
							declaring  a  LUN  path off-
							line.
							Range: 0 - 0xFFFFFFFE
       ------------------------------------------------------------------------------
		   esd_secs		RW     uint32	Maximum time in seconds  for
							the transmission of an I/O.
							Range: 0 - 0xFFFFFFFF
       ------------------------------------------------------------------------------
		   max_q_depth		RW     uint32	Maximum queue depth.
							Range: 1 - 0xFFFFFFFE
       ------------------------------------------------------------------------------
		   load_bal_policy	RW     string	I/O load balancing policy.
							May be set to:
							round_robin
							least_cmd_load
							cl_round_robin
							closest_path
							weighted_rr
       ------------------------------------------------------------------------------

		   alua_enabled 	RW     boolean	Indicates whether Asymmetric
							Logical Unit  Access  (ALUA)
							functionality  is enabled by
							default.  A  value  of	true(1)    indicates   that   by
							default  ALUA  functionality
							will   be  handled  for  the
							devices  supporting  it.   A
							value of false(0) indicates
							that by default  ALUA  func-
							tionality  will  be  ignored
							for the  devices  supporting
							it.
							May be:
							true(1): enable ALUA
							false(0): disable ALUA
       ------------------------------------------------------------------------------
		   disable_flags	RW     string	A  set of flags representing
							SCSI  task  management	 and
							other  functions.  If a flag
							is  set,  the  corresponding
							function is disabled for the
							set of devices.
							The following flags are cur-
							rently defined:
							WCE: Write Cache Enable
							RW16:  16  bytes  READ/WRITE
							CDB
							ABT:  SCSI  task  management
							function Abort Task Set
							CTS:  SCSI  task  management
							function Clear Task Set
							LR:  SCSI  task   management
							function LUN Reset
							WTR:  SCSI  task  management
							function Warm Target Reset
							CTR:  SCSI  task  management
							function Cold Target Reset
							BR: Bus Reset
							PR: Persistent Reservation
							WERO: Write Exclusive Regis-
							trants	  Only	  Persistent
							Reservation
							EARO:  Exclusive Access Reg-
							istrants   Only   Persistent
							Reservation
							ALL: Disable all functions
							NONE: Enable all functions
       ------------------------------------------------------------------------------
		   infinite_retries	RW     Boolean	Enable or  disable  infinite
		   _enable				retries of I/Os
							May be:
							true(1): enable
							false(0): disable
       ------------------------------------------------------------------------------

		   retry_delay		RW     boolean	Enables or disables  support
		   _enabled				of  retry  delay timer codes
							returned by devices  comply-
							ing  with SAM-4 (SCSI Archi-
							tecture Model 4), in case of
							congestion.  If set to false(0), retry delay timer codes
							are ignored.  If set to true(1), retry delay timer codes
							are  taken  into  considera-
							tion, when handling  conges-
							tion.
							May be:
							true(1): enable retry delay
							timer codes.
							false(0):  disable  disable
							retry delay timer codes.
       ------------------------------------------------------------------------------
		   ping_type		RW     string	Failed LUN path connectivity
							test.	Determines   whether
							the  system should automati-
							cally test the	connectivity
							of  a failed LUN path and if
							so which kind of  test	must
							be performed.
							May be set to:
							No  connectivity test should
							be performed.
							Basic	connectivity	test
							including  Standard  Inquiry
							command,  should   be	per-
							formed.
							Extended  connectivity	test
							including  Standard  Inquiry
							and  Test  Unit  Ready (TUR)
							commands  should   be	per-
							formed.
       ------------------------------------------------------------------------------
		   ping_recovery	RW     string	Failed	 LUN  path  recovery
							policy.  Determines  when  a
							failed	LUN  path  should be
							considered back online	when
							automatic  connectivity test
							is enabled.
							May be set to:
							Upon a successful connectiv-
							ity test.
							after  a  number of consecu-
							tive successful  onnectivity
							tests	specified   by	 the
							attribute
							Upon  sustained   successful
							connectivity   tests  within
							the time period specified in
							the attribute
       ------------------------------------------------------------------------------
		   ping_time  _thresh-	RW     uint32	Minimum time in seconds,  of
		   old					sustained successful connec-
							tivity tests before a failed
							LUN  path is considered back
							online.
							Range: 0 - 0xFFFFFFFF
       ------------------------------------------------------------------------------

		   ping_count _thresh-	RW     uint32	Minimum  number  of consecu-
		   old					tive successful connectivity
							tests  before  a  failed LUN
							path  is   considered	back
							online.
							Range: 0 - 0xFFFFFFFF
       ------------------------------------------------------------------------------

   I/O Load Balancing Policy
       The I/O load balancing policy attribute, is a tunable that controls how I/Os are distributed across the paths to a LUN:

	 o

	    LUN  paths	are  selected  in  a round robin manner.  This is more appropriate when all the paths to the device have similar I/O turn-
	    around characteristics.

	 o

	    The LUN path with the least number of active I/O requests is selected to execute the next I/O.  This policy is  appropriate  when  the
	    paths to the LUN exhibit asymmetric latency characteristics.  The load is distributed to optimize the bandwidth on each LUN path.

	 o

	    This  load	balancing  policy is applicable to HP cell-based platforms.  The LUN paths are selected in a round robin manner within the
	    locality of CPU on which the I/O was initiated, to ensure that memory access latencies are optimized.

	 o

	    The LUN path set in the attribute is preferably used for I/O transfer.  If this LUN path is not available or if the attribute was  not
	    set,  any  other  path is selected for I/O transfer.  This policy is useful for certain disk arrays, where some paths may be optimized
	    for I/O transfer to certain LUNs.

	    The attribute can be set with the hardware path, or the combination of the class and instance number of the preferred LUN  path.   For
	    example  for a LUN path with instance number 100, the combination of class and instance number is: In a normal output display for this
	    attribute, both the hardware path and the combination of class and instance number of the preferred LUN path are  displayed  (Example:
	    In scriptable output for this attribute, only the hardware path of the preferred LUN path is displayed (Example:

	 o

	    The  LUN path is selected based on its affinity with the CPU issuing the I/O so as to minimize latency.  This policy is more appropri-
	    ate on cell based platforms.

	 o

	    LUN paths to the target port set in the attribute are preferably used for I/O transfer in a round robin manner, when the I/O load bal-
	    ancing  policy  is	set to If no LUN path to the preferred target port is available, or if the attribute is not set, any other path is
	    selected for I/O transfer.	This policy is appropriate for certain disk arrays, where some target ports are optimized for I/O transfer
	    to certain LUNs.

	 o

	    Weighted Round Robin.  I/Os are distributed between the LUN paths in a round robin manner and according to the weight assigned to each
	    path (via the LUN path attribute A number of I/Os corresponding to the weight of the path is transferred on the  path  before  another
	    path is selected.

EXAMPLES

       To display plug-in general help and supported commands:

       To get esdisk driver global statistics:

       To clear esdisk driver global statistics:

       To get esdisk driver global status information:

       To display information about esdisk driver global attributes:

       To set the I/O load balancing policy for disk0 to and set the I/O path to be used preferably:

       To set the I/O load balancing policy for disk1 to and set the preferred target port to 0x50001fe150006e6d:

       To add a settable attribute scope corresponding to all disk devices from HP with product identifier "MSA VOLUME", for allowing modification
       of some settable attribute at this scope:

       To persistently change the default I/O load balancing policy, I/O timeout, and maximum concurrent I/O  for all disk devices  from  HP  with
       product identifier "MSA VOLUME:"

       To disable write cache, Persistent Reservation and 16 bytes read/write CDB for all disk devices bound to the driver:

AUTHOR

       SCSI class driver plug-in for was developed by Hewlett-Packard Company.

SEE ALSO

       diskinfo(1M), scsictl(1M), scsimgr(1M), intro(7), scsi(7), scsi_disk(7).

																 scsimgr_esdisk(7)