Open SCSI Integrator's Manual for NonStop S-Series Servers

Open SCSI Integrator’s Manual for NonStop Servers—422988-002
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4
The Open SCSI I/O Process (IOP)
This section describes software topics associated with writing device drivers to interface
with the Open SCSI I/O process (IOP), including Common Access Method (CAM)
control blocks (CCBs). CAM operations, and IOP status values. This section includes
the following topics:
•
Logical Units (LUNs) on page 4-1
•
Guardian Procedure Calls on page 4-1
•
Using the FILE_OPEN_ Procedure on page 4-2
•
Using the WRITEREAD[X] Procedures on page 4-3
•
Structure of the WRITEREAD Buffer on page 4-5
•
SIM Queue Operations on page 4-15
•
IOP Status Values on page 4-15
Logical Units (LUNs)
The Open SCSI IOP supports the attachment of separately addressable and controllable
logical units (LUNs) to an external device on the SCSI bus. Note the following points:
•
You can define up to eight LUNs for a SCSI target ID on the SCSI bus.
•
The target device through which LUNs operate is itself always assigned the logical
unit number LUN0. The LUNs that operate with a given target device are assigned
the logical unit numbers LUN1 through LUN7.
•
The configuration software, through its use of logical devices, treats all LUNs
including LUN0 as individually addressable and configurable entities. Note that the
term “device” in the documentation can refer to any logical device.
Guardian Procedure Calls
The Open SCSI IOP provides support for the following Guardian procedure calls:
•
FILE_OPEN_
•
WRITEREAD[X]
•
AWAITIO[X]
•
CANCELREQ
•
DEVICE_GETINFOBYLDEV_
•
DEVICE_GETINFOBYNAME_
•
FILE_CLOSE_
•
FILE_GETINFO_
•
FILE_GETINFOBYNAME_
•
FILE_GETINFOLIST_
•
FILE_GETINFOLISTBYNAME_