Full Volatility; Full Fabric - McDATA StorageWorks 2/140 - Director Switch Planning Manual

Physical Planning Considerations
5

Full Volatility

Full Fabric

McDATA Products in a SAN Environment - Planning Manual
5-38
The figure illustrates two Intrepid 6064 Directors connected by two
ISLs. Three servers use the ISLs to communicate with two storage
devices. Without trunking, servers 1 through 3 route Fibre Channel
traffic from to director B without regard to any data rates. A possible
scenario is that servers 1 and 2 route high data rate traffic through
ISL 1 to storage device 1 (ISL oversubscription) and server 3
routes low data rate traffic through ISL 2 to storage device 2
(ISL undersubscription).
Preferred path configurations are more restrictive than, and take
precedence over, OpenTrunking. Even if OpenTrunking is enabled,
no attempt is made to reroute traffic away from a preferred path,
even if the path is congested or BB_Credit starved.
Full volatility is a feature (available on directors and fabric switches
with E/OSc Version 6.0 and later) that supports military, classified, or
other high-security environments that require Fibre Channel data not
be retained by the director or fabric switch after power off or failure.
When a director or fabric switch (without the full volatility feature
installed) powers off or fails, a dump file is written to non-volatile
random-access memory (NV-RAM). This dump file retains the last 30
Fibre Channel frames transmitted from the embedded port and the
last four frames transmitted to the embedded port.
These Fibre Channel frames are then written to diskette and included
as part of the data collection procedure. This process constitutes a
security breach if the frame data includes classified information.
With the full volatility feature installed and enabled, no frame data is
stored and the NV-RAM dump does not occur when the director or
switch powers off or fails. Although this feature limits the diagnostic
information available for fault isolation and resolution, the majority
of failures are resolved without the dump file.
The Sphereon 4300 Fabric Switch is delivered without E_Port (ISL)
functionality and with all ports set to a BB_Credit value of 5. With the
full fabric feature installed and enabled, switch E_Port functionality
is provided and all port BB_Credit values are increased to 12. This
feature is provided only for the Sphereon 4300 Fabric Switch.