1. Introduction
   1.1. Project/Component Working Name:
	New subclass for DR class events

   1.2. Name of Document Author/Supplier:
	Author: Dolpher Du/River Li

   1.3. Date of This Document:
   	1 June, 2007

4. Technical Description:
1) Background
=============

	The sfx-4500 disk monitor, which  is used to monitor the  status of 
	disk, requires  the mpt HBA driver  to generate notification events
	when sata  drives are removed  or inserted. The mpt  HBA controller
	hardware  provides  asynchronous message  mechanism  to notify  HBA
	driver  about target  hotplug. When  mpt HBA  driver  receives such
	messages, it should generate EC_DR events and reports them to upper
	level consumers.
	
2) Problem
==========

	The EC_DR  event class was  defined in PSARC 2000/189.  It contains
	two  subclasses:  ESC_DR_AP_STATE_CHANGE  and ESC_DR_REQ,  both  of
	which  are  designed  to  reflect  the  status  change  of  dynamic
	attachment   point.  The  dynamic   attachment  point   defined  in
	cfgadm(1M)  is  a  lun   based  conception  for  SCSI,  not  target
	based.  For the  SCSI/SAS HBAs  that are  target  status sensitive,
	those two type of events are not feasible since the host HBA driver
	can't get  the notification  of single lun  online or  offline from
	hardware  if the  target keeps  connection. In  other  respect, the
	existing  event subclasses  are not  convenient for  consumers that
	only care for target status change.

3) Solution
===========

	We propose a new subclass belonging  to the EC_DR class. It is used
	to describe target status change, and defined as following:
	
	ESC_DR_TARGET_STATE_CHANGE (per target state change event)
	
	Description - Indicate a cable connection state change
	Commitment Level - "Consolidation Private"

	Event Class 	- EC_DR
	Event Sub-Class - ESC_DR_TARGET_STATE_CHANGE
	Event Publisher	- SUNW:kern:<driver-name>
	Attribute Name	- TARGET_ID
	Attribute Type	- [SE_DATA_TYPE_STRING]
	Attribute Value	- </physical_path_to_hba:target>
	Attribute Name	- HINT
	Attribute Type	- [SE_DATA_TYPE_STRING]
	Attribute Value	- "" | "insert" | "remove" | ...	

	For example,  a sata disk is  connected to LSI  SAS controller, and
	marked as target 5. The physical  path of the LSI SAS controller is
	/devices/pci@7c0/pci@0/pci@1/pci@0,2/LSILogic,sas@1.  When the sata
	disk  is   removed  physically,   mpt  driver  will   generate  the
	ESC_DR_TARGET_STATE_CHANGE   event.   Its   TARGET_ID  payload   is
	/devices/pci@7c0/pci@0/pci@1/pci@0,2/LSILogic,sas@1:5,  and HINT is
	"remove".
	
	This event  will be first  used by mpt  driver, but the  concept of
	target id is not limited to  SCSI, it's common enough for other HBA
	drivers to use.

5. Reference Documents:
	PSARC 2000/189
	PSARC/1998/424

6. Resources and Schedule:
   6.4. Product Approval Committee requested information:
   	6.4.1. Consolidation or Component Name:
		ON
   6.5. ARC review type:
		FastTrack