Compex Systems Advanced SerialRAID Adapters SA33-3285-02 - Manual (Page 275)

Chapter 13. Using the Programming Interface
SSA Subsystem Overview
Device Drivers
Two types of device driver provide support for all SSA subsystems:
v The SSA adapter device driver, which deals with the SSA adapter.
v The SSA head device drivers, which deal with devices that are attached to the SSA
adapter. The SSA disk device driver is an example of an SSA head device driver.
For subsystems that use the Micro Channel SSA Multi-Initiator/RAID EL Adapter, the
PCI SSA Multi-Initiator/RAID EL Adapter, or the Advanced SerialRAID Adapter, the
Target-Mode SSA (TMSSA) device driver is also available. This device driver provides
support for communications from using system to using system. For information about
SSA Target Mode and the TMSSA device driver, see “SSA Target Mode” on page 291.
Responsibilities of the SSA Adapter Device Driver
The SSA adapter device driver provides a consistent interface to all SSA head device
drivers, of which the SSA disk device driver is an example.
The SSA adapter device driver sends commands for SSA devices to the adapter that is
related to those devices. When the SSA adapter device driver detects that the
commands have completed, it informs the originator of the command.
Responsibilities of the SSA Disk Device Driver
The SSA disk device driver provides support for the SSA disk drives that are connected
to an SSA adapter. That support consists of:
v Standard block I/O to SSA logical disks, which are represented as hdisks
v Character mode I/O to SSA logical disks, which are represented as rhdisks
v Error reporting from SSA physical disks, which are represented as pdisks
v Diagnostics and service interface to SSA physical disks that are represented as
pdisks
v Re-issue of commands in the event of an adapter reset
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