Sun Microsystems Virtual Tape Library - Manual (Page 30)

16 VTL User Guide • May 2008 G • 96267
Zoning for high‐availability systems
Zoning a high‐availability system is slightly more complex than zoning a standard
system, due to the need for redundant paths between initiators and targets. Once
again, each SAN zone can have only one initiator and one target. But the total
number of zones you need depends on whether the SAN is soft‐zoned (by World
Wide Port Name) or hard‐zoned (by port number). See:
■ “WWPN zoning (soft zoning)” on page 16
■
“Port zoning (hard zoning)” on page 17.
WWPN zoning (soft zoning)
A soft‐zoned SAN maps initiator to target using a logical World Wide Port Name
(WWPN), rather than a physical hardware address. This name‐to‐name zoning
establishes a logical route that may traverse varying physical ports and varying
physical paths through the SAN. To accomplish failover, we thus need only a single
zone for the client initiator, the active VTL target, and the standby VTL target.
See the figure below shows a soft‐zoned SAN before VTL failover :
During failover, the zone still contains only one initiator and one target at a time. But
the target WWPN is remapped from a port on the failed server node to a physical
port on the standby server. The standby physical port spoofs the WWPN of the
failed port, so zoning does not change. The figure below shows a soft‐zoned SAN
after VTL failover, with a standby port spoofing the WWPN of the failed port:
Zone A
T
I
I
Client A
Active VTL server node A
T
I
Standby VTL server node A
SAN
WWPN2 WWPN1
WWPN3
Zone B
I
Client B
WWPN5
WWPN4 WWPN6
Active VTL server node B
Standby VTL server node B