Driver components – HP StoreEver MSL6480 Tape Library User Manual
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A failover device driver must identify devices accessible over the different paths available and
associate paths with devices so that it is able to mask duplicate paths and present a single path
to an ISV application.
As devices are discovered by the operating system and the DEVICE OBJECT is passed into the
driver for initialization, the driver determines if the device is a tape or changer device and is a
candidate for failover. If the device is a candidate for failover, the driver determines the serial
number (SN) or worldwide name (WWN) of the device.
If the device is capable of advanced path failover, the driver determines whether failover is enabled
for the device. If the device does support failover and failover is enabled, then the driver will mask
all duplicate paths and present a single path to application clients. If the device does not support
failover, if failover is not enabled, or if an error occurred while attempting to determine the
failover-enabled state, then the driver will not modify the presentation of paths to the device to
applications.
Driver components
Windows advanced path failover drivers consists of two drivers: a storage bus filter driver and an
intermediate class driver. The storage bus filter driver processes OS device notifications (PnP
notifications) to identify available paths to tape and media changer devices capable of supporting
advanced path failover. The intermediate class driver works with the devices that have been
identified as advanced path failover capable devices and manages the active paths to the changer
and tape drives.
This architecture follows the architecture of Microsoft’s MPIO. MPIO only supports disk devices
and cannot be used directly.
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.
Windows driver theory of operation
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