User`s guide

B – Glossary
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Driver (continued) In NetWare, the required drivers include:
■ Host Adapter Module (HAM). HAM is the driver
component associated with the host adapter
hardware. It provides the functionality to route
requests to the bus where a specified device is
attached.
■ Custom Device Module (CDM). CDM is the drive
component associated with storage devices. It
provides the functionality to build device-specific
commands from I/O messages received from
NetWare’s Media Manager.
In Red Hat Linux, the driver layers include:
■ SCSI Upper Layer. This is the device management
layer. It handles device-dependent tasks for devices,
such as disks and tapes.
■ SCSI Middle Layer. This is the SCSI traffic handling
layer. It directs requests between the kernel and the
SCSI.
■ SCSI Lower Layer. This is the SCSI host bus adapter
driver. It communications directly to the SCSI HBA.
The structure for Solaris SPARC drivers includes:
■ Nexus Drivers. Nexus drivers provide bus mapping
and translation services to subordinate nexus and
leaf devices. These include drivers for PCI-to-PCI
bridges, PCMCIA adapters, and SCSI HBAs.
■ Leaf Drivers. Leaf drivers provide the traditional
character and block driver interfaces for reading and
writing data to storage and communication devices.
These include drivers for peripheral devices,
including QLA2xxx adapters, disks, tapes, network
adapters, and frame buffers.
Fabric A fabric consists of cross-connected Fibre Channel
devices and switches.
Fabric switch A fabric switch connects multiple devices from
independent Fibre Channel-arbitrated loops (FC-ALs)
and point-to-point topologies into a fabric.