HP StoreEver MSL6480 Tape Library User and Service Guide Addendum (QU625-96016, October 2013)

The library controller appears as a third independent device even though it is sharing the physical
connection with one of the tape drives. The logical view and physical connections for a library
using NPIV and configured to use library control path port failover is shown in Figure 9 (page 17).
Figure 9 NPIV virtual library connection
1 2
2. Logical direct link to switch1. Physical link to switch sharing drive link
With NPIV creating a virtual device on the switch port to which the drive is connected, both the
tape drive and the tape library are shown by the switch as independent devices even though they
are connected to the same physical port. Because the library is presented to the host as an
independent device it can be managed independently from the tape drive.
In “NPIV virtual library connection” (page 17), the tape library contains two drives with both tape
drives connected to a Fibre Channel switch. The library is presented as a virtual device using the
same link one of the tape drives in the figure.
When the tape library detects that the control path should fail over to an alternate path it is able
to disconnect the library from the physical link and reconnect the library to the switch over the link
used by the other drive without disrupting that link. Both drives could be active reading or writing
and the library can be moved without disrupting the drive activity. The logical connection following
a control path failover event is shown in Figure 10 (page 18).
Technology for drive-assisted failover 17