HP StoreOnce Backup System Concepts and Configuration Guidelines (BB877-90913, November 2013)

6 Fibre Channel considerations
The HP StoreOnce B6200 Backup system supports switched fabric using NPIV only. All other HP
StoreOnce Backup systems support both switched fabric and direct attach (private loop) topologies.
Switched fabric using NPIV (N Port ID Virtualisation) offers a number of advantages and is the
preferred topology for all StoreOnce appliances.
NOTE: As with networking the multi-node StoreOnce B6200 Backup system has specific FC
considerations to ensure support for autonomic failover. This chapter contains generic information
about FC support. See also Configuring FC to support failover with the HP StoreOnce B6200
Backup system (page 47).
• Virtual library devices are assigned to an individual interface. Therefore, for best performance,
configure both FC ports and balance the virtual devices across both interfaces to ensure that
one link is not saturated whilst the other is idle.
• Switched fabric mode is preferred for optimal performance on medium to large SANs since
zoning can be used. Switched fabric mode is required for the HP B6200 Backup system.
• Use zoning (by Worldwide Name) to ensure high availability.
• When using switched fabric mode, Fibre Channel devices should be zoned on the switch to
be only accessible from a single backup server device. This ensures that other SAN events,
such as the addition and removal of other FC devices, do not cause unnecessary traffic to be
sent to devices. It also ensures that SAN polling applications cannot reduce the performance
of individual devices.
• Either or both of the two FC ports may be connected to a FC fabric and each virtual library
may be associated with one or both of these FC ports but each drive can only be associated
with one port. Port 1 and 2 is the recommended option in the GUI to achieve efficient load
balancing. Only the robotics (medium changer) part of the VTL is presented to Port 1 and Port
2 initially, with the number of virtual tape drives defined being presented 50% to Port 1 and
50% to Port 2. This also ensures that in the event of a fabric failure at least half of the drives
will still be available to the hosts. (The initial virtual tape drive allocation to ports (50/50) can
be edited later, if required.
Port assignment for StoreOnce Backup systems with two Fibre Channel
cards
StoreOnce B6200, 4900 and 4700 model only: These models have two FC cards per server; there
are four FC ports (B6200: available on each node). When creating a library you may select
individual drives or FC ports 1&2 or FC ports 3&4. Be aware that Port 1 and port 3 are on the
first FC card; port 2 and port 4 are on the second FC card, so it is important to ensure that the
system has been cabled correctly when connecting to the FC SAN. If you select one of the combined
port options, both FC cards must be connected.
Drives can only appear on one port, so when you choose a pair of ports, drives are automatically
distributed evenly across both ports to ensure best performance and failover. After creating the
library, it is possible to change the drive assignments using the edit function on the Interface
Information tab for the selected library.
Port assignment for StoreOnce Backup systems with two Fibre Channel cards 41