User's Manual

Figure 15 (page 38) shows the organization of the Windows drivers and the system components
when an Emulex LPe12002 host bus adapter is installed. In this example, the tape drive presents
both SSC (tape) and SMC (media changer) device servers. Not all drives in the library will present
an SMC device server.
Figure 15 Driver and system organization
Storage bus filter driver
The storage bus filter driver is named HPtapeFailover_filt and manages the OS notifications
indicating that devices have been added or removed. The storage bus filter driver bus enumerator
is usually "PCI". It attaches as an upper filter to all HBA drivers. It then monitors the creation of
raw devices, looking for supported failover capable devices. Requests to all other devices are
passed through unchanged. When a supported device is recognized, the hardware ID of the
device is changed to a value that the upper device driver will recognize, but that the rest of the
system will not. The special hardware ID prevents the standard tape class driver from attaching to
the raw paths.
38 Installing and using Windows advanced path failover drivers