8-2
Cisco MDS 9000 Family NX-OS Interfaces Configuration Guide
OL-29284-01, Release 6.x
Chapter 8 Configuring FlexAttach Virtual pWWN
Information About FlexAttach Virtual pWWN
• Replacement to the same port—A failed server can be replaced onto the same port without changing
the SAN. The new server gets a same pWWN as the failed server because the virtual pWWN is
assigned to the port.
• Replacement to (spare)—A spare server, which is on the same NPV device or a different NPV
device) can be brought online without changes to the SAN. This action is achieved by moving the
virtual port WWN from the current server port to the spare port.
• Server Mobility—A server can be moved to another port on the same NPV device or another NPV
device without changing the SAN. This is accomplished by moving the virtual pWWN to the new
port. No change is needed if FlexAttach was configured using the physical port WWN of the server
to the virtual port WWN mapping.
Difference Between San Device Virtualization and FlexAttach Port
Virtualization
Table 8-1 describes the difference between SAN device virtualization (SDV) and FlexAttach port
virtualization.
Ta b l e 8-1 Difference Between SDV and FlexAttach Virtualization
FlexAttach Virtual pWWN CFS Distribution
The FlexAttach virtual pWWN configuration is distributed for CFS through IPv4, and is enabled by
default. The FlexAttach virtual pWWN distribution, by default, is on CFS region 201. The CFS region
201 links only to the NPV-enabled switches. Other CFS features such as syslog is on region 0. Region 0
will be linked through IPv4 for all NPV switches on the same physical fabric. If CFS has an option to
link through IPv4 or ISL, then CFS will select the ISL path.
Note NPV switches do not have ISL (E or TE ports) and are linked through IPv4.
SAN Device Virtualization (SDV) FlexAttach Virtualization
Facilitates target and disk management, and only
facilitates disk and data migration.
Facilitates server management and has no
restriction on the end devices used.
WWN NAT and Fibre Channel ID (FC-ID) are
allocated on the virtual device, both primary and
secondary.
WWN and Network Address Transport (NAT) is
allocated to host bus adapter (HBA).
FC-ID rewrite on the switch indicates a
rewrite-capable switch on the path.
No rewrite requirements.
Configuration is distributed. This allows
programming rewrites and connectivity
anywhere.
Configuration distribution is not required for any
of the interface-based configurations.
Configuration is secured to device alias. Does not require device alias for virtual pWWN.
Does not allow automapping to the secondary
device.
Allows automapping to the new HBA. Mapping
process is manual for NPIV.
