The worldwide name-to-target ID mapping on each cluster member must
be symmetrically assigned.
For more information on the
emx
driver, see
emx
(7)
.
In a typical shared parallel SCSI configuration, the SCSI target IDs
are assigned by means of console-level commands, console firmware
settings, jumpers, or other hardware implementations. In a Fibre Channel
configuration, the Tru64 UNIX system uses a number of files to create
and maintain a persistent mapping of target IDs to Fibre Channel device
worldwide names. This mechanism may appear to be a bit out of the
ordinary. However, the general concepts are virtually identical, and this is
an important consideration when you install or replace Fibre Channel-based
hardware.
4.6.1 Initial Worldwide Name-to-Target ID Mapping
After you install Fibre Channel hardware, the worldwide name-to-target ID
mapping is set up, on a first-device-encountered basis, the first time that
the member system is booted. The software does the mapping so you do
not have to take any action. After the system is operational, the target ID
mapping is written to the
emx
driver data and backup files,
/etc/emx.db
and
/etc/emx.db.bak
. The database allows the mapping to persist across
power cycles and reboots. A text version of the database file is written to
/etc/emx.info
.
The mapping is done on a first-device-encountered basis. Therefore, if you
boot all cluster member systems, each system might have a different target
ID mapping and the contents of the
/etc/emx.db
and
/etc/emx.db.bak
files might be different between systems. To prevent this, the assignment of
target ID mapping must be synchronized.
4.6.2 Synchronizing the Initial Assignment of Target IDs in a Cluster
To ensure that all cluster member systems have the same target ID
mapping at initial boot, follow these steps. In the case of arbitrated loop
configurations, a maximum of two member systems is supported. However,
the same process applies.
1.
Make sure that all member systems are powered up and fully connected
to shared storage. Additionally, make sure that all HSG80 controllers
have storage sets defined, are powered up, and properly connected to
a Fibre Channel switch or hub.
2.
Boot all cluster member systems but one to single-user mode as follows:
>>>
boot -fl s
4–20 Installing Fibre Channel Hardware and Configuring the emx Driver