
running member. The software makes appropriate entries in both the
daemon.log
file and the hardware error log (for use by CompaqAnalyze.)
5.1.2 Fibre Channel Switch Failures
The Fibre Channel switch represents a single point of failure (SPOF) for each
shared SCSI bus that it serves. A total failure of one switch will cause the
entire shared bus to fail. Depending on how the storage is configured, this
failure can result in the loss of access to some or all of the data. If the cluster
has two switches and the critical data is mirrored using the Logical Storage
Manager (LSM) across the two buses, then there would be no interruption,
and you could resynchronize the data mirror after the switch is serviced.
You can manage the Fibre Channel switch through two different interfaces:
•
Telnet
•
A graphical user interface (GUI) using the World Wide Web
______________________
Note
_______________________
The Fibre Channel switch supports only one Telnet or one Web
session at a time.
Because the GUI interface to the Fibre Channel switch visually highlights a
failing port, it is most useful for quickly spotting a problem. To access the
GUI interface from your browser, use the URL
http://
nnn.nnn.nnn.nnn
(where the
http://
is mandatory and nnn.nnn.nnn.nnn is the IP address of
the switch.)
The Telnet interface is useful for managing the switch by typing commands
manually (making it potentially available to someone dialing in from outside
the facility using PPP and then starting a Telnet session), or by the use of
scripts. (A script could rapidly connect to the switches, obtain data, log out,
and then parse the information using various
awk
and
sed
commands to
determine what worldwide IDs (WWIDs) are logged into which switch ports,
or detect if a port failure has occurred.)
The
switchShow
command, for example, lists all of the information about
the current state of the switch, including all of its ports and the associated
WWID numbers of the devices logged into those ports. If a device fails,
the status of that port might change to
No_Light
, which is what the
switch reports when a cable is unplugged, or
In_Sync
to indicate that the
switch recognizes that a device is plugged in, but has not been properly
synchronized and logged in.
5–2 Troubleshooting and Component Replacement Guidelines