HP StoreEver MSL2024, MSL4048, MSL8048, and MSL8096 Tape Libraries User and Service Guide (AK378-96059, December 2012)

Table Of Contents
Figure 17 Library world wide name displayed on the Identity: Library page
Hosts connecting to the library may need to be rebooted if the operating system does not
support dynamic device detection.
Applications on hosts may need to be reconfigured to recognize the new library world wide
name.
Verifying control path failover
After enabling control path failover, verify the configuration of both ports. To verify both paths first
verify that the hosts configured for access to the library are able to communicate with the library.
It may be necessary to modify switch zoning to enable access to the library. After the host access
has been verified use the library front panel or the library management interface to power off the
drive marked as hosting the library logical unit number Drive 1 (LUN) in “Configuration: Drive
screen showing control path failover configuration disabled” (page 29) - Configure: Drives.
NOTE: There is always a library logical unit number hosted by a drive so the (LUN) indicator
does not change when control path failover is enabled. The library is presented as logical unit
number zero on its own world wide node name when control path failover is enabled and is
presented as logical unit number one on the drive world wide node name when control path failover
is not enabled.
After the library has powered off the drive hosting the library control path, the LUN indicator should
move to the alternate control path drive. When the library has reported that the drive has been
successfully powered off and the LUN indicator has moved to the alternate control path drive,
verify that host connectivity to the library has not changed. It may be necessary to configure switch
zoning to allow host access.
After verifying library connectivity using each of the library control paths, the library control path
may be moved back to the original drive if so desired by using the Alternate Drive for Library
Control Path option (see “Configure library, control path failover configuration available (page 30)).
Hardware-specific requirements
Brocade switches
For best reliability when control path failover is used Brocade switches should be running version
3.2.2e, 3.4.1b, or newer.
Cisco switches
Some Cisco switches that support NPIV do not have NPIV enabled by default. The Cisco MDS9148
may disable NPIV when power cycled.
Control path and data path failover 31