HP StoreEver MSL6480 Tape Library - Manual (Page 11)

Technology for basic control path failover
HP LTO-5 and LTO-6 Fibre Channel tape drives use a technology called N-Port Identifier
Virtualization (NPIV) which is defined as part of the Fibre Channel standards maintained by the
INCITS/T11 working group (see clause 6) in the FC-LS-2 specification. NPIV allows a single physical
port to connect to a Fibre Channel switch multiple times using multiple node and port names.
Advanced path failover
Advanced path failover uses capabilities in the LTO-6 tape drives and the libraries in which they
are installed, combined with software drivers running on a host system to provide path failover
when multiple paths are available to a tape drive or to a library controller. Advanced path failover
is a licensed feature.
An example multi-path configuration is shown in Figure 5 (page 11) .
Figure 5 Example multi-path configuration
In this example configuration, two different servers designated as “Server A” and “Server B” each
have two different host interface ports that are connected to two different SANs. Each SAN is
connected to the tape library. The connection between the library and the SAN in this example is
a bundle of connections that contains a connection to one port on each drive in the library. All of
the drives in the library have two ports with one port connected into SAN 1 and the second port
connected into SAN 2. The library in this example has two different drives which are both configured
to provide a library control path. Each drive that is configured to provide a library control path
will connect to the SAN as two devices, a tape drive and a library controller, at two different SCSI
logical units.
The list of paths available at one of the servers is shown in “Example path list” (page 12) . In this
table, the SAN that contains the path is listed in the first column and the following columns show
what device is being addressed (for example, the SCSI logical unit), the port on the drive that is
being accessed, an example SCSI address, and the worldwide identifier (such as a Fibre Channel
worldwide node name) of the addressed logical unit. The unique portion of the worldwide identifier
is highlighted.
Advanced path failover 11